Polymerizable materials

ABSTRACT

The present invention provides a polymerizable material for making a polymeric article, the polymerizable material comprising: a water-soluble polyvinyl alcohol having crosslinkable groups; and a modifier in an amount sufficient to improve one or more physical properties of a polymeric article made from the polymerizable material, wherein the one or more physical properties are selected from the group consisting of stress at break (N/mm 2 ), percentage of elongation at break, toughness or energy to break (N·mm), and susceptibility to fracture. The modifier is selected from the group consisting of nanoparticles having a hydrophilic surface, a copolymer having hydrophobic groups or units for imparting at least one desired physical property to said ophthalmic device and hydrophilic groups or units in an amount sufficient to render the copolymer miscible with the polyvinyl alcohol, and mixtures thereof. In addition, the present invention provides a polymeric article obtained by polymerization of a polymerizable material of the invention and also a method for modifying one or more physical properties of a hydrogel article obtained from the polymerization of a crosslinkable polymer.

This application claims the benefit under USC §119)e) of U.S.provisional application No. 60/420,626 filed Oct. 23, 2002, and isincorporated by reference in it's entirety.

The present invention is related to polymerizable materials useful formaking polymeric articles, preferably ophthalmic devices, morepreferably soft contact lenses. In particular, the present invention isrelated to a composition comprising a water-soluble, crosslinkablepolyvinyl alchohol with crosslinkable groups and a modifier capable ofimparting at least one desired physical property of an ophthalmic devicemade from the composition. The present invention is also related to amethod for making a polymeric article, preferably ophthalmic devices,more preferably soft contact lenses from polymerizable materials of theinvention. In addition, the present invention is related to a method forpreparing a polymeric article having at least one desired physicalproperty.

BACKGROUND

It is well known that contact lenses can be used for cosmetics and thecorrection of visual acuity. The ideal contact lens is one which is notonly comfortable to wear for extended periods of time, but also easilyand reproducibly manufactured at minimum cost in time and labor.

Contact lenses can be manufactured economically in large numbers by theso-called mold or full-mold process. Known contact lens-moldingprocesses are described in, for example, PCT patent application no.WO/87/04390 or in EP-A 0 367 513. In a typical molding process, apredetermined amount of a polymerizable or crosslinkable material isplaced in the female mold half and the mold is closed by placing themale mold half proximately to the female mold half to create a cavityhaving a desired geometry for a contact lens. Normally, a surplus ofpolymerizable or crosslinkable material is used so that when the maleand female halves of the mold are closed, the excess amount of thematerial is expelled out into an overflow area adjacent to the moldcavity. The polymerizable or crosslinkable material remaining within themold is polymerized or cross-linked with the delivery of radiationthereto through UV light, heat action, or another non-thermal methods.Since the geometry of the ophthalmic lens is specifically defined by thecavity between the male and female mold halves and since the geometry ofthe edge of the ophthalmic lens is defined by the contour of the twomold halves in the area where they make contact, a contact lens ismanufactured into a final form between typically male and female moldhalves, with no additional finishing work on the surface of the lens orthe edges of the lens. Such full-mold process can reduce cost in theproduction of contact lenses. However, in a typical molding process, acontact lens, which is removed from the mold after curing, needs toundergo the other manufacturing processes such as hydration/extractionand sterilization. Therefore, there is still room for further reducingmanufacturing cost of contact lenses.

U.S. Pat. Nos. 5,508,317, 5,583,463, 5,789,464, and 5,849,810 describean improved manufacturing process for economically producing contactlenses in large numbers. By using a prepolymer which is a water-solublephoto-crosslinkable polyvinyl alcohol, a finished lens of opticalquality can be produced in a mold within a few seconds without thenecessity for subsequent extraction or finishing steps to the contactlens. With such manufacturing process, contact lenses can bemanufactured at considerably low cost and thus it is possible to producedisposable contact lenses that are discarded by the user after a singleuse.

Although contact lenses manufactured by one of the processes disclosedby U.S. Pat. Nos. 5,508,317, 5,583,463, 5,789,464, and 5,849,810 haveadvantageous properties such as a good compatibility with the humancornea resulting in a relatively high wearing comfort and the absence ofirritation and allergenic effects, a need for further improvement stillremains. For example, problems may sometimes show up in production ofcontact lenses from a water-soluble photo-crosslinkable polyvinylalcohol. In particular, during mold opening and removing the contactlenses from the mold, cracks, flaws or tears may occur in the lenses orin the worst case the contact lenses even break totally. Contact lenseshaving such defects have to be discarded and lower the overallproduction yield. In addition, contact lenses made from a water-solublephoto-crosslinkable polyvinyl alcohol do not always posses all of mostdesirable physical properties, for example, such as elasticity anddurability, for the intended uses.

One object of the invention is to provide a polymerizable compositionuseful for economically producing soft contact lenses having improveddurability, elasticity and/or other desired physical properties.

Another object of the invention is to provide an improved method foreconomically producing soft contact lenses having improved durability,elasticity and/or other desired physical properties.

SUMMARY OF THE INVENTION

In accomplishing the foregoing, there is provided, in accordance withone aspect of the present invention, a polymerizable material for makinga polymeric article, the polymerizable material comprising: awater-soluble polyvinyl alcohol having crosslinkable groups; and amodifier in an amount sufficient to improve one or more physicalproperties of a polymeric article made from the polymerizable material,wherein the one or more physical properties are selected from the groupconsisting of stress at break (N/mm²), percentage of elongation atbreak, toughness or energy to break (N·mm), and susceptibility tofracture.

In another aspect, the present invention provides a polymeric articlewhich is a product of radiation-crosslinking of an above-describedpolymerizable material of the invention in the presence or preferably inthe absence of one or more additional vinylic monomers.

In a further aspect, the present invention provides an ophthalmicdevice, preferably a soft contact lens, which is obtained bycrosslinking an above-described polymerizable material of the inventionin the presence or preferably in the absence of one or more additionalvinylic monomers.

In another further aspect, the present invention provides a method forproducing an ophthalmic device, the method comprising the steps of: a)introducing an above-described polymerizable material of the invention,in the presence or preferably in the absence of one or more additionalvinylic comonomers, and optionally in the presence of a photo-initiator,into a mold; b) crosslinking by actinic radiation the polymerizablematerial, and c) opening the mold so that the ophthalmic device can beremoved from the mold.

In still a further aspect, the present invention provides a method formodifying one or more physical properties of a hydrogel article obtainedfrom the polymerization of a crosslinkable polymer, the methodcomprising the steps of: adding, into a solution of said crosslinkablepolymer, a modifier in an amount sufficient to modify said one or morephysical properties of said polymeric article, wherein said modifier isselected from the group consisting of nanoparticles having a hydrophilicsurface, a copolymer having hydrophobic groups or units for imparting atleast one desired physical property to said hydrogel article andhydrophilic groups or units in an amount sufficient to render itmiscible with the crosslinkable polymer, and mixtures thereof; mixingthoroughly said modifier and the crosslinkable polymer; and crosslinkingsaid crosslinkable polymer in the presence of the modifier to obtainsaid hydrogel article, wherein the one or more physical properties areselected from the group consisting of stress at break (N/mm²),percentage of elongation at break, toughness or energy to break (N·mm),and susceptibility to fracture.

These and other aspects of the invention will become apparent from thefollowing description of the preferred embodiments. As would be obviousto one skilled in the art, many variations and modifications of theinvention may be effected without departing from the spirit and scope ofthe novel concepts of the disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference now will be made in detail to the embodiments of theinvention. It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope or spirit of the invention. Forinstance, features illustrated or described as part of one embodiment,can be used on another embodiment to yield a still further embodiment.Thus, it is intended that the present invention cover such modificationsand variations as come within the scope of the appended claims and theirequivalents. Other objects, features and aspects of the presentinvention are disclosed in or are obvious from the following detaileddescription. It is to be understood by one of ordinary skill in the artthat the present discussion is a description of exemplary embodimentsonly, and is not intended as limiting the broader aspects of the presentinvention.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Generally, the nomenclatureused herein and the laboratory procedures are well known and commonlyemployed in the art. Conventional methods are used for these procedures,such as those provided in the art and various general references. Wherea term is provided in the singular, the inventors also contemplate theplural of that term. The nomenclature used herein and the laboratoryprocedures described below are those well known and commonly employed inthe art.

In one aspect, the present invention relates to a polymerizable materialfor making an ophthalmic device, preferably a contact lens. Apolymerizable material of the invention comprises: a water-solublepolyvinyl alcohol having crosslinkable groups; and a modifier in anamount sufficient to improve one or more physical properties of apolymeric article made from the polymerizable material, wherein the oneor more physical properties are selected from the group consisting ofstress at break (N/mm²), percentage of elongation at break, toughness orenergy to break (N·mm), and susceptibility to fracture.

“Improvement in the stress at break (N/mm²) of an ophthalmic device”means that the ophthalmic device, prepared from a composition composedof a water-soluble polyvinyl alcohol having crosslinkable groups and amodifier, has an increased value of the stress at break relative to anophthalmic device prepared from a composition composed of awater-soluble polyvinyl alcohol without the modifier.

“Improvement in the percentage of elongation at break, of an ophthalmicdevice” means that the ophthalmic device, prepared from a compositioncomposed of a water-soluble polyvinyl alcohol having crosslinkablegroups and a modifier, has an increased value of percentage ofelongation at break relative to an ophthalmic device prepared from acomposition composed of a water-soluble polyvinyl alcohol without themodifier.

“Improvement in the toughness or energy to break (N·mm) of an ophthalmicdevice” means that the ophthalmic device, prepared from a compositioncomposed of a water-soluble polyvinyl alcohol having crosslinkablegroups and a modifier, has an increased value of the toughness or energyto break (N·mm) relative to an ophthalmic device prepared from acomposition composed of a water-soluble polyvinyl alcohol without themodifier.

“Improvement in susceptibility to fracture of an ophthalmic device”means that the ophthalmic device, prepared from a composition composedof a water-soluble polyvinyl alcohol having crosslinkable groups and amodifier, is less susceptible to fracture relative to an ophthalmicdevice prepared from a composition composed of a water-soluble polyvinylalcohol without the modifier.

An “ophthalmic device”, as used herein, refers to a contact lens (hardor soft), an intraocular lens, a corneal onlay, and other ophthalmicdevices (e.g., stents, implants, or the like) used on or about the eyeor ocular vicinity. An ophthalmic device according to the invention ispreferably a soft contact lens, more preferably a hydrogel contact lens.

A “crosslinkable group”, as used herein, refer to a photocrosslinkableor thermally crosslinkable group well known to the person skilled in theart. Crosslinkable groups such as those already proposed for thepreparation of contact lens materials are especially suitable. Thoseinclude especially, but not exclusively, groups comprising carbon-carbondouble bonds.

A “radiation-curable prepolymer” refers to a starting polymer which canbe crosslinked upon actinic radiation to obtain a crosslinked polymerhaving a molecular weight much higher than the starting polymer.Examples of actinic radiation are UV irradiation, ionized radiation(e.g. gamma ray or X-ray irradiation), microwave irradiation, and thelike.

A “hydrophilic vinylic monomer” refers to a monomer which as ahomopolymer typically yields a polymer that is water-soluble or canabsorb at least 10 percent by weight water.

A “hydrophobic vinylic monomer” refers to a monomer which as ahomopolymer typically yields a polymer that is insoluble in water andcan absorb less than 10 percent by weight water.

A water-soluble crosslinkable poly(vinyl alcohol) according to theinvention is preferably a polyhydroxyl compound which has a molecularweight of at least about 2000 and which comprises from about 0.5 toabout 80%, based on the number of hydroxyl groups in the poly(vinylalcohol), of units of the formula I, II and II, I and III, or I and IIand III

A “molecular weight”, as used herein, refers to a weight averagemolecular weight, Mw, determined by gel permeation chromatography,unless otherwise specified.

In formula I, II and III, R₃ is hydrogen, a C₁-C₆ alkyl group or acycloalkyl group.

In formula I, II and III, R is alkylene having up to 12 carbon atoms,preferably up to 8 carbon atoms, and can be linear or branched. Suitableexamples include octylene, hexylene, pentylene, butylene, propylene,ethylene, methylene, 2-propylene, 2-butylene and 3-pentylene. Loweralkylene R preferably has up to 6, particularly preferably up to 4carbon atoms. Methylene and butylene are particularly preferred.

In the formula I, R₁ is hydrogen or lower alkyl having up to seven, inparticular up to four, carbon atoms. Most preferably, R₁ is hydrogen.

In the formula I, R₂ is an olefinically unsaturated,electron-withdrawing, crosslinkable radical, preferably having up to 25carbon atoms. In one embodiment, R₂ is an olefinically unsaturated acylradical of the formula R₄—CO—, in which R₄ is an olefinicallyunsaturated, crosslinkable radical having 2 to 24 carbon atoms,preferably having 2 to 8 carbon atoms, particularly preferably having 2to 4 carbon atoms.

The olefinically unsaturated, crosslinkable radical R₄ having 2 to 24carbon atoms is preferably alkenyl having 2 to 24 carbon atoms, inparticular alkenyl having 2 to 8 carbon atoms, particularly preferablyalkenyl having 2 to 4 carbon atoms, for example ethenyl, 2-propenyl,3-propenyl, 2-butenyl, hexenyl, octenyl or dodecenyl. Ethenyl and2-propenyl are preferred, so that the —CO—R₄ group is the acyl radicalof acrylic acid or methacrylic acid.

In another embodiment, the radical R₂ is a radical of the formula IV,preferably of the formula V—CO—NH—(R₅—NH—CO—O)_(q)R₆—O—CO—R₄  (IV)—[CO—NH—(R₅—NH—CO—O)_(q)R₆—O]_(p)—CO—R₄  (V)in which p and q, independently of one another, are zero or one, and R₅and R₆, independently of one another, are lower alkylene having 2 to 8carbon atoms, arylene having 6 to 12 carbon atoms, a saturated bivalentcycloaliphatic group having 6 to 10 carbon atoms, arylenealkylene oralkylenearylene having 7 to 14 carbon atoms or arylenealkylenearylenehaving 13 to 16 carbon atoms, and in which R₄ is as defined above.

Lower alkylene R₅ or R₆ preferably has 2 to 6 carbon atoms and is, inparticular, linear. Suitable examples include propylene, butylene,hexylene, dimethylethylene and, particularly preferably, ethylene.

Arylene R₅ or R₆ is preferably phenylene, which is unsubstituted orsubstituted by lower alkyl or lower alkoxy, in particular 1,3-phenyleneor 1,4-phenylene or methyl-1,4-phenylene.

A saturated bivalent cycloaliphatic group R₅ or R₆ is preferablycyclohexylene or cyclohexylene(lower alkylene), for examplecyclohexylenemethylene, which is unsubstituted or substituted by one ormore methyl groups, for example trimethylcyclohexylenemethylene, forexample the bivalent isophorone radical.

The arylene unit of alkylenearylene or arylenealkylene R₅ or R₆ ispreferably phenylene, unsubstituted or substituted by lower alkyl orlower alkoxy, and the alkylene unit thereof is preferably loweralkylene, such as methylene or ethylene, in particular methylene.Radicals R₅ or R₆ of this type are therefore preferablyphenylenemethylene or methylenephenylene.

Arylenealkylenearylene R₅ or R₆ is preferably phenylene(loweralkylene)phenylene having up to 4 carbon atoms in the alkylene unit, forexample phenyleneethylenephenylene.

The radicals R₅ and R₆ are preferably, independently of one another,lower alkylene having 2 to 6 carbon atoms, phenylene, unsubstituted orsubstituted by lower alkyl, cyclohexylene or cyclohexylene(loweralkylene), unsubstituted or substituted by lower alkyl, phenylene(loweralkylene), (lower alkylene)phenylene or phenylene(loweralkylene)phenylene.

In the formula II, R₇ is a primary, secondary or tertiary amino group ora quaternary amino group of the formula N⁺(R′)₃X⁻, in which each R′,independently of the others, is hydrogen or a C₁-C₄ alkyl radical and Xis a counterion, for example HSO₄ ⁻, F⁻, Cl⁻, Br⁻, I⁻, CH₃ COO⁻, OH⁻,BF⁻, or H₂PO₄ ⁻.

The radicals R₇ are, in particular, amino, mono- or di(loweralkyl)amino, mono- or diphenylamino, (lower alkyl)phenylamino ortertiary amino incorporated into a heterocyclic ring, for example —NH₂,—NH—CH₃, —N(CH₃)₂, —NH(C₂H₅), —N(C₂H₅)₂, —NH(phenyl), —N(C₂H₅)phenyl or

In the formula III, R₈ is the radical of a monobasic, dibasic ortribasic, saturated or unsaturated, aliphatic or aromatic organic acidor sulfonic acid. Preferred radicals R₈ are derived, for example, fromchloroacetic acid, succinic acid, glutaric acid, adipic acid, pimelicacid, maleic acid, fumaric acid, itaconic acid, citraconic acid, acrylicacid, methacrylic acid, phthalic acid and trimellitic acid.

For the purposes of this invention, the term “lower” in connection withradicals and compounds denotes, unless defined otherwise, radicals orcompounds having up to 7 carbon atoms, preferably having up to 4 carbonatoms.

Lower alkyl has, in particular, up to 7 carbon atoms, preferably up to 4carbon atoms, and is, for example, methyl, ethyl, propyl, butyl ortert-butyl.

Lower alkoxy has, in particular, up to 7 carbon atoms, preferably up to4 carbon atoms, and is, for example, methoxy, ethoxy, propoxy, butoxy ortert-butoxy.

The bivalent group —R₅—NH—CO—O— is present if q is one and absent if qis zero. Poly(vinyl alcohol)s containing crosslinkable groups in which qis zero are preferred.

The bivalent group —CO—NH—(R₅—NH—CO—O)q-R₆—O— is present if p is one andabsent if p is zero. Poly(vinyl alcohol)s containing crosslinkablegroups in which p is zero are preferred.

In the poly(vinyl alcohol)s comprising units containing crosslinkablegroups in which p is one, the index q is preferably zero. Particularpreference is given to poly(vinyl alcohol)s comprising crosslinkablegroups in which p is one, the index q is zero and R₅ is lower alkylene.

In the formula N⁺(R′)₃X⁻, R′ is preferably hydrogen or C₁-C₃ alkyl, andX is halide, acetate or phosphite, for example —N⁺(C₂H₅)₃CH₃COO—,—N⁺(C₂H₅)₃Cl⁻, and —N⁺(C₂H₅)₃H₂PO₄ ⁻.

A water-soluble crosslinkable poly(vinyl alcohol) according to theinvention is more preferably a polyhydroxyl compound which has amolecular weight of at least about 2000 and which comprises from about0.5 to about 80%, preferably from 1 to 50%, more preferably from 1 to25%, even more preferably from 2 to 15%, based on the number of hydroxylgroups in the poly(vinyl alcohol), of units of the formula 1, wherein Ris lower alkylene having up to 6 carbon atoms, R₁ is hydrogen or loweralkyl, R₃ is hydrogen, and R₂ is a radical of formula (V). Where p iszero, R₄ is preferably C₂-C₈ alkenyl. Where p is one and q is zero, R₆is preferably C₂-C₆ alkylene and R₄ is preferably C₂-C₈ alkenyl. Whereboth p and q are one, R₅ is preferably C₂-C₆ alkylene, phenylene,unsubstituted or lower alkyl-substituted cyclohexylene or cyclohexylene-lower alkylene, unsubstituted or lower alkyl-substitutedphenylene-lower alkylene, lower alkylene-phenylene, or phenylene-loweralkylene-phenylene, R₆ is preferably C₂-C₆ alkylene, and R₄ ispreferably C₂-C₈ alkenyl.

A water-soluble crosslinkable poly(vinyl alcohol) according to theinvention has a molecular weight of at least about 2000.

Crosslinkable poly(vinyl alcohol)s comprising units of the formula I, Iand II, I and III, or I and II and III can be prepared in a manner knownper se. For example, U.S. Pat. Nos. 5,583,163 and 6,303,687 disclose andteach how to prepare crosslinkable polymers comprising units of theformula I, I and II, I and II, or I and II and III.

A water-soluble crosslinkable poly(vinyl alcohol) according to theinvention is preferably in extremely pure form, for example, in the formof concentrated aqueous solutions that are free, or at leastsubstantially free, from reaction products and starting materials (e.g.,salts, non-polymeric constituents). Purification can be carried outaccording to any techniques known to a person skilled in the art, forexample, by precipitation with acetone, dialysis or ultrafiltration. Apreferred purification process is ultrafiltration, which can be carriedout repeatedly, e.g., from two to ten times, or continuously until aselected degree of purity is achieved. A suitable measure for the degreeof purity is, for example, the sodium chloride concentration of thesolution.

A modifier according to the invention is a material the presence ofwhich in a polymerizable material can improve at least one physicalproperty of an ophthalmic device made from the polymerizable material.Examples of physical properties are stress at break (N/mm²), percentageof elongation at break, toughness or energy to break (N·mm), andsusceptibility to fracture.

In one embodiment, a modifier is composed of nanoparticles having ahydrophilic surface. Exemplary nanoparticles having a hydrophilicsurface are nano-sized silica fillers.

In another embodiment, a modifier is composed of one or more copolymerseach having hydrophilic groups or units in an amount sufficient torender it miscible with the water-soluble polyvinyl alcohol andhydrophobic groups or units for imparting at least one desired physicalproperty to said ophthalmic device.

In another embodiment, a modifier is composed of a mixture ofnanbparticles having a hydrophilic surface and at least one copolymerhaving hydrophilic groups or units in an amount sufficient to render itmiscible with the water-soluble polyvinyl alcohol and hydrophobic groupsor units for imparting at least one desired physical property to thepolymeric article made from the polymerizable material.

It has been discovered here that although it is possible to find ahomopolymer of hydrophilic monomer (such as, for example, poly(vinylpyrrolidone) (PVP) or a dextrane) to be miscible with a water-solublepolyvinyl alcohol, blending of such hydrophilic homopolymer with thewater-soluble polyvinyl alcohol does not allow to make contact lenseshaving a significantly improved physical property. However, it is foundthat by blending a copolymer, having a balanced composition ofhydrophilic and hydrophobic groups or units, with a water-solublepolyvinyl alcohol, it is possible to prepare a contact lens having atleast one significantly improved physical property. It is believed thathydrophilic groups or units miscible with the water-soluble polyvinylalcohol should be present in an amount sufficient to ensure a desiredmiscibility of the copolymer with the water-soluble polyvinyl alcohol.While the claimed invention is not limited to the theory developed tosupport this unexpected result, a proposed theory is presented herein inorder to enable the reader to better understand the invention. It isbelieved that, in a polymeric article obtained by polymerizing awater-soluble polyvinyl alcohol in the presence of a copolymer having abalanced composition of hydrophilic and hydrophobic groups or units, thehydrophilic groups or units the copolymer are intertwined with thepolymer meshwork of polyvinyl alcohol, whereas the hydrophobic groups orunits may form nano-composites or microscopically co-continuous phases.Such nano-composites or microscopically co-continuous phases may impartone or more improved physical properties to the polymeric article.

It is understood that a copolymer, having a balanced composition ofhydrophilic and hydrophobic groups or units, as a modifier in accordancewith the present invention can optionally contain crosslinkable groups.By having crosslinkable groups, a copolymer can be covalently anchoredto the polymeric meshwork in a polymeric article. With such covalentattachment of a modifier, there is no need for subsequent extraction orfinishing steps to the contact lenses produced from a compositioncomposed of a water soluble polyvinyl alcohol and a modifier neitherconcerns about the possibility of leaching out of a modifier fromcontact lenses. Therefore, contact lenses can be manufactured atconsiderably low cost and it is possible to produce disposable contactlenses that are discarded by the user after a single use.

Where a copolymer used as a modifier does not contain crosslinkablegroups, it preferably has a relatively high molecular weight.

Any known suitable copolymer having a balanced composition ofhydrophilic and hydrophobic groups or units can be used in the presentinvention. A person skilled in the art will know well how to select acopolymer as a modifier and how to make a copolymer according to anyknown suitable method.

One example of a copolymer as a modifier is a non-crosslinkablepolyurethane or a crosslinkable polyurethane. For example, a modifieraccording to the present invention is a vinyl group-terminatedpolyurethane, which is prepared by reacting an isocyanate-cappedpolyurethane with an ethylenically unsaturated amine (primary orsecondary amine) or an ethylenically unsaturated monohydroxy compound.

An isocyanate-capped polyurethane according to the invention is acopolymerization product of

-   (a) at least one polyalkylene glycol of formula    HO—(R₉—O)_(n)—(R₁₀—O)_(m)—(R₁₁—O)_(l)—H  (1)    -   wherein R₉, R₁₀, and R₁₁, independently of one other, are each        linear or branched C₂-C₄-alkylene, and n, m and l, independently        of one another, are each a number from 0 to 100, wherein the sum        of (n+m+l) is 5 to 100,-   (b) at least one branching agent selected from the group consisting    of    -   (i) a linear or branched aliphatic polyhydroxy compound of        formula        R₁₂—(OH)_(x)  (2),    -   wherein R₁₂ is a linear or branched C₃-C₁₈ aliphatic        multi-valent radical and x is a number ≧3,    -   (ii) a polyether polyol, which is the polymerization product of        a compound of formula (2) and a glycol,    -   (iii) a polyester polyol, which is the polymerization product of        a compound of formula (2), a dicarboxylic acid or a derivative        thereof and a diol, and    -   (iv) a cycloaliphatic polyol selected from the group consisting        of a C₅-C₈-cycloalkane which is substituted by ≧3 hydroxy groups        and which is unsubstituted by alkyl radical, a C₅-C₈-cycloalkane        which is substituted by ≧3 hydroxy groups and which is        substituted by one or more C₁-C₄ alkyl radicals, and an        unsubstituted mono- and disaccharide,    -   (v) an aralkyl polyol having at least three hydroxy C₁-C₄ alkyl        radicals, and-   (c) at least one di- or polyisocyanate of formula    R₁₃—(NCO)_(y)  (3)    -   wherein R₁₃ a linear or branched C₃-C₂₄ aliphatic        polyisocyanate, the radical of a C₃-C₂₄ cycloaliphatic or        aliphatic-cycloaliphatic polyisocyanate, or the radical of a        C₃-C₂₄ aromatic or araliphatic polyisocyanate, and y is a number        from 2 to 6.

In formula (1), n, m and l, independently of one another, preferablyeach denote a number from 0 to 50, whereby the sum of (n+m+l) is 8 to50. Most preferably, n, m and l, independently of one another, eachdenote a number from 0 to 25, whereby the sum of (n+m+l) is 9 to 25.

In formula (1), where l is zero, n and m, independently of one another,are each a number from 0 to 100, preferably 0 to 50, and most preferably0 to 25, and the sum of (n+m) is 5 to 100, preferably 8 to 50, mostpreferably 9 to 25.

In formula (1), where l and m are each 0, n is a number from 5 to 100,preferably 8 to 50, most preferably 9 to 25.

Exemplary poly(alkylene glycol)s include, but are not limited to apoly(ethylene glycol), a poly(propylene glycol), a poly(ethyleneglycol)/poly(propylene glycol) block-polymer, a poly(ethyleneglycol)/poly(propylene glycol)/poly(butylene glycol) block polymer, apolytetrahydrofuran, a poloxamer, and mixtures thereof.

Poloxamers are hydroxy terminated tri-block copolymers with thestructure PEG-PPG-PEG (where “PEG” is poly(ethylene glycol) and “PPG” ispoly(propylene glycol)) and are available, for example, under thetradename PLURONIC®. The order of PEG and PPG blocks can be reversedcreating block copolymers with the structure PPG-PEG-PPG, which areavailable, for example, under the tradename PLURONIC-R®). A considerablenumber of poloxamers is known, differing merely in the molecular weightand in the PEG/PPG ratio. Examples are poloxamer 101, 105, 108, 122,123, 124, 181, 182, 183, 184, 185, 188, 212, 215, 217, 231, 234, 235,237, 238, 282, 284, 288, 331, 333, 334, 335, 338, 401, 402, 403 and 407.Poloxamer 101 has a PEG/PPG weight ratio of about 10/90 and poloxamer108 having a PEG/PPG weight ratio of about 80/20.

Polyoxypropylene-polyoxyethylene block copolymers can also be designedwith hydrophilic blocks comprising a random mix of ethylene oxide andpropylene oxide repeating units. To maintain the hydrophilic characterof the block, ethylene oxide will predominate. Similarly, thehydrophobic block can be a mixture of ethylene oxide and propylene oxiderepeating units. Such block copolymers are available under the tradenamePLURADOT®.

The weight average molecular weight of poloxamers may vary within widelimits. An average molecular weight of, may be, for example, from about1000 to 20000, preferably from 1000 to 15000, more preferably from 1000to 8000 and in particular from 1000 to 5000.

A branching agent of formula (2) is preferably a linear or branched C₃to C₁₂ aliphatic polyol, more preferably a linear or branched C₃ to C₈aliphatic polyol. The variable x in formula (2) is preferably a numberfrom 3 to 12, more preferably a number from 3 to 8, even more preferablya number from 3 to 6, and most preferably the number 3.

Examples of a branching agent of formula (2) are glycerol, diglycerol,triglycerol, 1,1,1-trishydroxymethylethane,1,1,1-trishydroxymethylpropane, 1,2,4-butanetriol, 1,2,6-hexanetriol,erythritol, pentaerythritol, di- or tripentaerythritol, arabitol,sorbitol, disorbitol or mannitol and mixtures thereof. Preferredcompounds of formula (2) are glycerol, 1,1,1-tris-hydroxymethylpropane,1,2,4-butanetriol, erythritol, pentaerythritol, arabitol or sorbitol. Agroup of preferred branching agents of formula (2) comprises glycerol,1,1,1-tris-hydroxymethylpropane, pentaerythritol, and pentaerythritolethoxylate.

Further suitable as a branching agent according to (b) are reactionproducts of the above-mentioned polyhydroxy compounds of formula (2)with a dicarboxylic acid, a dicarboxylic acid anhydride, a dicarboxylicacid ester, a dicarboxylic acid halide, or a diol.

Where at least one branching agent according to (b) is a polyesterpolyol, the branching agent is preferably an oligomeric reaction productof a compound of formula (2), wherein the above-mentioned meanings andpreferences apply, with an aliphatic or cycloaliphatic dicarboxylic acidhaving 3 to 12 carbon atoms, or an aromatic dicarboxylic acid having 5to 15 carbon atoms, or an appropriate derivative thereof, e.g. acorresponding dicarboxylic acid anhydride, ester or halide, as well as adiol as chain extender. Examples of suitable dicarboxylic acids aremalonic acid, succinic acid, 2,2-dimethylsuccinic acid, glutaric acid,adipic acid, pimelic acid, sebacic acid, tetrahydrophthalic acid,hexahydrophthalic acid, phthalic acid, isophthalic acid, terephthalicacid, maleic acid or fumaric acid, as well as the correspondingdicarboxylic acid esters, halides or anhydrides. Appropriate diols aree.g. linear or branched C₂-C₂₀-alkyl-diols.

Where at least one branching agent according to (b) is a cycloaliphaticpolyol, the branching agent may be e.g. cyclopentane or preferably acyclohexane, which is respectively substituted by 3 to 5 and preferablyby 3 or 4 hydroxy groups and bears no further substituents or heteroatoms. Further suitable cycloaliphatic polyols according to (b) arerepresented by unsubstituted mono- or disaccharides, e.g. glucose,fructose, mannose, galactose, maltose, lactose or saccharose.

In formula (3), y is preferably a number from 2 to 4, more preferably 2.

Where y is 2 in the formula (3), R₁₃ is the radical of a linear orbranched C₃-C₁₈-alkylene, an unsubstituted or C₁-C₄-alkyl-substituted orC₁-C₄-alkoxy-substituted C₆-C₁₀-arylene, a C₇-C₁₉-aralkylene, aC₆-C₁₁-arylene-C₁-C₂-alkylene-C₆-C₁₀-arylene, a C₃-C₈-cycloalkylene, aC₃-C₈-cycloalkylene-C₁-C₆-alkylene, aC₃-C₈-cycloalkylene-C₁-C₂-alkylene-C₃-C₈-cycloalkylene, or aC₁-C₆-alkylene-C₃-C₈-cycloalkylene-C₁-C₆-alkylene.

Where R₁₃ is the radical of an alkylene, R₁₃ is preferably a linear orbranched C₄-C₁₂-alkylene radical, more preferably a linear or branchedC₆-C₁₀-alkylene radical. Examples of preferred alkylene radicals are1,4-butylene, 2,2-dimethyl-1,4-butylene, 1,5-pentylene,2,2-dimethyl-1,5-pentylene, 1,6-hexylene, 2,2,3- or2,2,4-trimethyl-1,5-pentylene, 2,2-dimethyl-1,6-hexylene, 2,2,3- or2,2,4- or 2,2,5-trimethyl-1,6-hexylene, 2,2-dimethyl-1,7-heptylene,2,2,3- or 2,2,4- or 2,2,5- or 2,2,6-trimethyl-1,7-heptylene,1,8-octylene, 2,2-dimethyl-1,8-octylene or 2,2,3- or 2,2,4- or 2,2,5- or2,2,6- or 2,2,7-trimethyl-1,8-octylene.

Where R₁₃ is the radical of an arylene, the arylene is preferablynaphthylene, more preferably phenylene. If the arylene is substituted, asubstituent is preferably located in ortho position to an isocyanategroup. Examples of substituted arylene are 1-methyl-2,4-phenylene,1,5-dimethyl-2,4-diphenylene, 1-methoxy-2,4-phenylene or1-methyl-2,7-naphthylene.

Where R₁₃ is the radical of an aralkylene, the aralkylene is preferablynaphthylalkylene, more preferably phenylalkylene. The alkylene group inaralkylene preferably contains 1 to 12, more preferably 1 to 6, evenmore preferably 1 to 4, most preferably 1 to 2 C-atoms. A few examplesare 1,3- or 1,4-benzylene, naphth-2-yl-7-methylene, 6-methyl-1,3- or-1,4-benzylene, 6-methoxy-1,3- or -1,4-benzylene.

Where R₁₃ is the radical of a cycloalkylene, the cycloalkylene ispreferably C₅-C₆-cycloalkylene, more preferably cyclohexylene which isrespectively unsubstituted or methyl-substituted. A few examples are1,3-cyclobutylene, 1,3-cyclopentylene, 1,3- or 1,4-cyclohexylene, 1,3-or 1,4-cycloheptylene, 1,3- or 1,4- or 1,5-cyclooctylene,4-methyl-1,3-cyclopentylene, 4-methyl-1,3-cyclohexylene,4,4-dimethyl-1,3-cyclohexylene, 3-methyl- or3,3-dimethyl-1,4-cyclohexylene, 3,5-dimethyl-1,3-cyclohexylene,2,4-dimethyl-1,4-cyclohexylene.

Where R₁₃ is the radical of a cycloalkylene-alkylene, thecycloalkylene-alkylene is preferably cyclopentylene-C₁-C₄-alkylene, morepreferably cyclohexylene-C₁-C₄-alkylene which is respectivelyunsubstituted or substituted once or several times by C₁-C₄-alkyl,especially methyl. The group cycloalkylene-alkylene preferably denotescyclohexylene-ethylene and most preferably denotescyclohexylene-methylene, which is respectively unsubstituted in thecyclohexylene radical or substituted by 1 to 3 methyl groups. A fewexamples are cyclopent-1-yl-3-methylene,3-methyl-cyclopent-1-yl-3-methylene,3,4-dimethyl-cyclopent-1-yl-3-methylene,3,4,4-trimethyl-cyclopent-1-yl-3-methylene, cyclohex-1-yl-3- or-4-methylene, 3- or 4- or 5-methyl-cyclohex-1-yl-3- or -4-methylene,3,4- or 3,5-dimethyl-cyclohex-1-yl-3- or -4-methylene, 3,4,5- or 3,4,4-or 3,5,5-trimethyl-cyclohex-1-yl-3- or -4-methylene.

Where R₁₃ is the radical of an alkylene-cycloalkylene-alkylene, thealkylene-cycloalkylene-alkylene is preferablyC₁-C₄-alkylene-cyclopentylene-C₁-C₄-alkylene and especiallyC₁-C₄-alkylene-cyclohexylene-C₁-C₄-alkylene, which is respectivelyunsubstituted or substituted once or several times by C₁-C₄-alkyl, mostpreferably methyl. The group alkylene-cycloalkylene-alkylene preferablydenotes ethylene-cyclohexylene-ethylene and most preferablymethylene-cyclohexylene-methylene, which is respectively unsubstitutedin the cyclohexylene radical or substituted by 1 to 3 methyl groups. Afew examples are cyclopentane-1,3-dimethylene,3-methyl-cyclopentane-1,3-dimethylene3,4-dimethyl-cyclopentane-1,3-dimethylene,3,4,4-trimethyl-cyclopentane-1,3-dimethylene, cyclohexane-1,3- or-1,4-dimethylene, 3- or 4- or 5-methyl-cyclohexane-1,3- or-1,4-dimethylene, 3,4- or 3,5-dimethyl-cyclohexane-1,3- or-1,4-dimethylene, 3,4,5- or 3,4,4- or 3,5,5-trimethyl-cyclohexane-1,3-or -1,4-dimethylene.

Where R₁₃ is the radical of a cycloalkylene-alkylene-cycloalkylene, thecycloalkylene-alkylene-cycloalkylene is preferablyC₅-C₆-cycloalkylene-methylene-C₅-C₆-cycloalkylene, which mayrespectively be unsubstituted in the cycloalkyl ring by one or moremethyl groups.

Where R₁₃ is the radical of an arylene-alkylene-arylene, thearylene-alkylene-arylene is preferably phenylene-methylene-phenylene,which may respectively be unsubstituted in the phenyl ring by one ormore methyl groups.

Examples of especially preferred diisocyanates of formula (3) areisophorone diisocyanate (IPDI), methylenebis(cyclohexyl-isocyanate),1,6-diisocyanato-2,2,4-trimethyl-n-hexane (TMDI),methylenebis(phenyl-isocyanate) or hexamethylene-diisocyanate (HMDI).

Examples of ethylenically unsaturated monohydroxy compound includes,without limitation, hydroxy-substituted lower alkylacrylates and-methacrylates, hydroxy-substituted lower alkyl-acrylamides and-methacrylamides, hydroxy-substituted lower alkylvinyl-ethers. Examplesof hydroxy-substituted lower alkylacrylates and -methacrylates are2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate.

An ethylenically unsaturated amine has formula (4), (4′) or (4″)

In which, i, j and k, independent of one another, are o or 1;

-   -   R₁₄ is hydrogen, a linear or branched C₁-C₂₄ alkyl, a C₂-C₂₄        alkoxyalkyl, a C₂-C₂₄ alkylcarbonyl, a C₂-C₂₄ alkoxycarbonyl, an        unsubstituted or C₁-C₄ alkyl- or C₁-C₄ alkoxy-substituted C₆-C₁₀        aryl, a C₇-C₁₈ aralkyl, a C₁₃-C₂₂ arylalkylaryl, a C₃-C₈        cycloalkyl, a C₄-C₁₄ cycloalkylalkyl, a C₇-C₁₈        cycloalkylalkylcycloalkyl, a C₅-C₂₀ alkylcycloalkylalkyl, or an        aliphatic-heterocyclic radical;    -   Z is a C₁-C₁₋₂ alkylene radical, phenylene radical or C₇-C₁₂        aralkylene radical;    -   R₁₅ and R₁₅′, independently of each other, are hydrogen, C₁-C₄        alkyl or halogen; and    -   Q is an ethylenically unsaturated copolymerizable radical having        from 2 to 24 carbon atoms which may be further substituted.

Aryl R₁₄ is a carbocyclic aromatic radical, which is unsubstituted orsubstituted by preferably lower alkyl (C₁-C₄) or lower alkoxy (C₁-C₄).Examples are phenyl, toluyl, xylyl, methoxyphenyl, t-butoxyphenyl,naphthyl or phenanthryl.

Cycloalkyl R₁₄ is preferably C₅-C₆ cycloalkyl and most preferablycyclohexyl that is unsubstituted or substituted by methyl. Some examplesare cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl,4-methyl-cyclopentyl, 4-methyl-cyclohexyl, 4,4-dimethyl-cyclohexyl,3-methyl- or 3,3-dimethyl-cyclohexyl, 3,5-dimethyl-cyclohexyl and2,4-dimethyl-cyclohexyl.

When R₁₄ is cycloalkylalkyl, it is preferably cyclopentyl-C₁-C₄ alkyland especially cyclohexyl-C₁-C₄ alkyl, each unsubstituted or mono- orpoly-substituted by C₁-C₄ alkyl, especially methyl. More preferably, thegroup cycloalkyl-alkyl is cyclohexylethyl and, most preferably,cyclohexylmethyl, each unsubstituted or substituted in the cyclohexylradical by from 1 to 3 methyl groups.

When R₁₄ is alkylcycloalkylalkyl, it is preferably C₁-C₄alkyl-cyclopentyl-C₁-C₄ alkyl and especially C₁-C₄alkyl-cyclohexyl-C₁-C₄ alkyl, each unsubstituted or mono- orpoly-substituted by C₁-C₄ alkyl, especially methyl. More preferably, thegroup alkylcycloalkylalkyl is ethylcyclohexylethyl and, most preferably,is methylcyclohexylmethyl, each unsubstituted or substituted in thecyclohexyl radical by from 1 to 3 methyl groups.

When R₁₄ is cycloalkylalkylcycloalkyl or arylalkylaryl, it is preferablyC₅-C₆ cycloalkyl-methyl-C₅-C₆ cycloalkyl or phenylmethylphenyl, each ofwhich may be unsubstituted or substituted in the cycloalkyl or phenylring by one or more methyl groups.

Suitable substituents on the ethylenically unsaturated C₂-C₂₄ radical Qare, for example, C₁-C₄ alkoxy, halogen, phenyl or carboxy.

Q is, for example, a radical of formula

wherein r is the number 0 or 1,

-   -   each of R₁₆ and R₁₇ independently of the other is hydrogen,        C₁-C₄ alkyl, phenyl, carboxy or halogen,    -   R₁₈ is hydrogen, C₁-C₄ alkyl or halogen, and    -   Z′ is linear or branched C₁-C₁₋₂ alkylene or unsubstituted or        C₁-C₄ alkyl- or C₁-C₄ alkoxy-substituted phenylene or C₇-C₁₂        aralkylene.

When Z′ is a phenylene radical, it is, for example, unsubstituted ormethyl- or methoxy-substituted 1,2-, 1,3- or 1,4-phenylene. Preferably,Z′ as a phenylene radical is 1,3- or 1,4-phenylene.

When Z′ is an aralkylene radical, it is, for example, unsubstituted ormethyl- or methoxy-substituted benzylene, wherein the methylene group isbonded to the amine nitrogen in each case. Preferably, Z′ as anaralkylene radical is the 1,3- or 1,4-phenylenemethylene radical,wherein the methylene group is bonded to the amine nitrogen —NH— in eachcase.

Z′ is preferably unsubstituted or methyl- or methoxy-substitutedphenylene or phenylenemethylene or C₁-C₁₋₂alkylene, more preferably 1,3-or 1,4-phenylene or C₁-C₆alkylene, especially C₁-C₂alkylene and mostpreferably methylene.

r is the number 1 or, preferably, the number 0.

R₁₈ is preferably hydrogen, methyl or chlorine and most preferablyhydrogen or methyl.

Each of R₁₆ and R₁₇, independently of the other, is preferably hydrogen,carboxy, chlorine, methyl or phenyl. In a preferred embodiment of theinvention, R₁₆ is hydrogen, chlorine, methyl or phenyl and R₁₇ ishydrogen or carboxy. Most preferably, R₁₆ and R₁₇ are each hydrogen.

Especially preferred radicals Q correspond to formula (5) wherein r is0, R₁₈ is hydrogen or methyl, R₁₆ is hydrogen, methyl, chlorine orphenyl and R₁₇ is hydrogen or carboxy.

Other especially preferred radicals Q correspond to the above formula(5) wherein r is 1, Z′ is 1,3- or 1,4-phenylene or C₁-C₆ alkylene,especially C₁-C₂ alkylene, R₁₈ is hydrogen or methyl and R₁₆ and R₁₇ areeach hydrogen.

Examples of suitable radicals Q are vinyl, 2-propenyl, allyl, 2-butenyl,o-, m- or p-vinylphenyl, vinylphenyl, vinylnaphthyl, allylphenyl,styryl, 2-carboxyvinyl, 2-chloro-2-carboxyvinyl,1,2-dichloro-2-carboxyvinyl, 1,2-dimethyl-2-carboxyvinyl and2-methyl-2-carboxyvinyl.

Examples of suitable ethylenically unsaturated amine are2-(ter-butylamino)ethylmethacrylate (TBAM), and vinyl aniline.

The isocyanate-capped polyurethane polymers according to the inventionmay be produced by following a solventless process.

For example, in a solventless process, first one or more polyalkyleneglycols of formula (1) (component (a)) is mixed with one or morebranching agents (component (b)) and the mixture is heated to andmaintained at a melting temperature or above. Then, at least one di- orpolyisocyanate of formula (3) (component (c)) is added to the meltedmixture to make a melted reaction mixture comprising component (a),component (b) and component (c) in a desired stoichiometry. Thetemperature of the melted reaction mixture is continuously andthoroughly stirred at the melting temperature or above and preferablyunder an inert atmosperic environment (for example, in nitrogen or argonatmosphere). Reaction is monitored by, for example, monitoring theisocyanate peak in FT-IR spectroscopy.

Components (a)-(c) are all known compounds or compound mixtures, or maybe obtained in accordance with methods known per se.

It should be understood that components (a), (b), and (c) can be mixedtogether in a desired stoichiometry and the mixture then can be meltedand maintained at a melting temperature or above to start reaction.

The stoichiometry of components (a), (b) and (c) in the melted reactionmixture is advantageously chosen so that the number of NCO equivalentsof component (c) is greater than the sum of OH equivalents of components(a) and (b). Preferably, the stoichiometry of components (a), (b) and(c) in the melted reaction mixture is chosen so that the molar ratio ofcomponent (a) to component (b) to component (c) is about 4:1:7.

It should be further understood that the isocayanate-capped polyurethanepolymers according to the invention may be produced by reactingcomponents (a), (b), and (c) and optionally additional copolymerizablemonomers in an inert solvent at a temperature of e.g. 30° C. to 150° C.

Suitable inert solvents are aprotic, preferably polar solvents, forexample hydrocarbon halides (chloroform, methylene chloride,trichloroethane, tetrachloroethane, chlorobenzene), ethers(tetrahydrofuran, dioxane), ketones (acetone, ethyl methyl ketone,dibutyl ketone, methyl isobutyl ketone), carboxylic acid esters andlactones (ethyl acetate, butyrolactone, valerolactone), alkylatedcarboxylic acid amides (N,N-dimethylacetamide, N-methylpyrrolidone),nitriles (acetonitrile), sulphones and sulphoxides (dimethyl sulphoxide,tetramethylene sulphone). Polar solvents are preferably employed.

Furthermore, it is preferable for the reaction of thehydroxy-group-containing components (a) and (b) with theisocyanate-group-containing components (c) to be carried out in thepresence of a catalyst, since the reaction time can be shortened.Suitable catalysts are for example metal salts such as alkali metalsalts or tin salts of organic carboxylic acids, or tertiary amines, forexample, (C₁-C₆-alkyl)₃N (triethylamine, tri-n-butylamine),N-methylpyrrolidine, N-methylmorpholine, N,N-dimethylpiperidine,pyridine or 1,4-diaza-bicyclooctane. Tin salts have proved to beparticularly effective, especially alkyl-tin salts of carboxylic acids,for example dibutyl tin dilaurate (DBTDL) and tin dioctoate.

The catalyst is employed in the reaction e.g. in a molar ratio of 1:10to 1:1000, preferably 1:50 to 1:750, most preferably ca. 1:100 to 1:500,respectively based on component (a).

The reaction times may vary within a broad range, whereby progress ofthe reaction can be followed well by monitoring the reduction of theisocyanate content in the reaction mixture.

It is particularly preferred that the isocyanate-capped polyurethanepolymers are produced in a solventless process. By using a solventlessprocess, the production cost associated with solvent and its disposalcan be eliminated.

Once the reaction of components (a) and (b) with component (c) iscompleted, the obtained isocyanate-capping polyurethane can be reacteddirectly with an ethylenically unsaturated amine (primary or secondaryamine) and an ethylenically unsaturated monohydroxy compound, to preparea vinyl group terminated polyurethane. Optionally, the obtainedisocyanate-capping polyurethane can be purified prior to the reaction.

Isolation and purification of the vinyl group-terminated polyurethaneare effected by known processes, for example extraction,crystallization, re-crystallization, ultrafiltration or bychromatographic purification methods. The compounds are obtained in highyields and with high purity.

The vinyl group-terminated polyurethanes according to the invention areradiation-curable, but uncrosslinked or at least substantiallyuncrosslinked; nevertheless, they are stable, i.e. spontaneouscrosslinking due to homopolymerization does not take placesubstantially. The term “radiation-curable” in reference to a prepolymermeans that the prepolymer can be crosslinked or polymerized by actinicradiation, including, for example, UV radiation, ionizing radiation suchgamma radiation or X-rays, microwave, and the like.

The average molecular weight of the vinyl group-terminated polyurethanesaccording to the invention may vary within a broad range. An averagemolecular weight of e.g. 1000 to 50,000 has proved to be advantageousfor the vinyl group-terminated polyurethanes according to the invention.

The above described isocyanate-capping polyurethane can also be used toprepared other non-crosslinkable polyurethanes, for example, by reactingwith water, amine, or the like.

Another example of a copolymer as a modifier in accordance with thepresent invention can be a copolymerization product of at least onehydrophilic monomer and at least one hydrophobic monomers, wherein thehomopolymer of said at least one hydrophilic monomer is miscible withthe water-soluble polyvinyl alcohol having crosslinkable groups.Exemplary preferred hydrophilic monomers include, but are not limitedto, hydroxy-substituted alkyl(meth)acrylates, N-vinyl-lactams,N,N-dialkyl-methacrylamides and vinylically unsaturated carboxylic acidswith a total of 3 to 5 carbon atoms.

A N-vinyl lactam in accordance with the invention has a structure offormula (VI)

wherein

-   -   R₁₉ is an alkylene di-radical having from 2 to 8 carbon atoms,    -   R₂₀ is hydrogen, alkyl, aryl, aralkyl or alkaryl, preferably        hydrogen or lower alkyl having up to 7 and, more preferably, up        to 4 carbon atoms, such as, for example, methyl, ethyl or        propyl; aryl having up to 10 carbon atoms, and also aralkyl or        alkaryl having up to 14 carbon atoms; and    -   R₂₁ is hydrogen or lower alkyl having up to 7 and, more        preferably, up to 4 carbon atoms, such as, for example, methyl,        ethyl or propyl.

Examples of N-vinyl lactams corresponding to the above structuralformula (VI) are N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone,N-vinyl-2-caprolactam, N-vinyl-3-methyl-2-pyrrolidone,N-vinyl-3-methyl-2-piperidone, N-vinyl-3-methyl-2-caprolactam,N-vinyl-4-methyl-2-pyrrolidone, N-vinyl-4-methyl-2-caprolactam,N-vinyl-5-methyl-2-pyrrolidone, N-vinyl-5-methyl-2-piperidone,N-vinyl-5,5-dimethyl-2-pyrrolidone,N-vinyl-3,3,5-trimethyl-2-pyrrolidone,N-vinyl-5-methyl-5-ethyl-2-pyrrolidone,N-vinyl-3,4,5-trimethyl-3-ethyl-2-pyrrolidone,N-vinyl-6-methyl-2-piperidone, N-vinyl-6-ethyl-2-piperidone,N-vinyl-3,5-dimethyl-2-piperidone, N-vinyl-4,4-dimethyl-2-piperidone,N-vinyl-7-methyl-2-caprolactam, N-vinyl-7-ethyl-2-caprolactam,N-vinyl-3,5-dimethyl-2-caprolactam, N-vinyl-4,6-dimethyl-2-caprolactamand N-vinyl-3,5,7-trimethyl-2-caprolactam.

A N-vinyl lactam according to the invention is preferably a heterocyclicmonomer of formula (VI) containing preferably from 4 to 6 carbon atoms,more preferably 4 carbon atoms in the heterocyclic ring, wherein R₂₀ andR₂₁ are each independently of the other hydrogen or lower alkyl.

A N-vinyl lactam copolymer can be prepared by copolymerization of atleast one N-vinyl lactam of formula (VI) with one or more hydrophobicmonomer according to any method known to a person skilled in the art.

Where the hydrophilic monomer is a N,N-dialkyl-methacrylamide, alkyl ispreferably methyl, ethyl, propyl, or butyl. N,N-dimethylacryamide is amore preferred embodiment of the hydrophilic monomer.

Where the hydrophilic monomer is a hydroxy-substitutedalkyl(meth)acrylate, alkyl is preferably methyl, ethyl, propyl, orbutyl.

Suitable hydrophobic monomers include, without limitation,C₁-C₁₈-alkylacrylates and -methacrylates, C₃-C₁₈ alkylacrylamides and-methacrylamides, acrylonitrile, methacrylonitrile,vinyl-C₁-C₁₈-alkanoates, C₂-C₁₈-alkenes, C₂-C₁₈-halo-alkenes, di-C₁-C₇alkylamino-C₁-C₇ alkylacrylate, styrene, C₁-C₆-alkylstyrene,vinylalkylethers in which the alkyl moiety has 1 to 6 carbon atoms,C₂-C₁₀-perfluoralkyl-acrylates and -methacrylates or correspondinglypartially fluorinated acrylates and methacrylates,C₃-C₁₂-perfluoralkyl-ethyl-thiocarbonylaminoethyl-acrylates and-methacrylates, acryloxy and methacryloxy-alkylsiloxanes,N-vinylcarbazole, C₁-C₁₂-alkylesters of maleic acid, fumaric acid,itaconic acid, mesaconic acid and the like. Preference is given e.g. toC₁-C₄-alkylesters of vinylically unsaturated carboxylic acids with 3 to5 carbon atoms or vinylesters of carboxylic acids with up to 5 carbonatoms.

In another aspect, the present invention relates to a polymeric articlewhich is a product of crosslinking of a polymerizable material of theinvention (described-above) in the presence or preferably in the absenceof one or more additional vinylic comonomers. The polymerizable materialof the invention may be crosslinked in an extremely effective andwell-directed manner upon actinic irradiation, in particular by UVirradiation. Crosslinking may take place in the presence or preferablyin the absence of an additional vinylic comonomer. The resultingcrosslinked polymers are insoluble in water, and preferably aresubstantially free of extractable chemicals.

A polymeric article according to the invention is an ophthalmic device,preferably a soft contact lens, more preferably a hydrogel contact lens.

In the case of photo-crosslinking, a photo-initiator is suitably addedwhich can initiate radical crosslinking. Examples of these are familiarto the person skilled in the art, and suitable photo-initiators whichmay be mentioned in particular are benzoin-methylether,1-hydroxy-cyclo-hexyl-phenylketone, Darocure® 1173 or Irgacure® types.Crosslinking may be commenced by actinic radiation, e.g. UV light, or byionized radiation, e.g. gamma rays or X-rays.

Photo-crosslinking is preferably effected directly from an aqueoussolution of a polymerizable material of the invention, which may beobtained as the result of the preferred purification step,ultrafiltration. For example, photo-crosslinking may be undertaken froma 15 to 90% aqueous solution.

The process for the production of polymeric articles according to theinvention comprises radiation-crosslinking an aqueous solution of apolymerizable material of the invention, the aqueous solution comprisingpreferably a photoinitiator and optionally a vinylic monomer.

The vinylic monomer which may be additionally used forphoto-crosslinking in accordance with the invention may be hydrophilic,hydrophobic or may be a mixture of a hydrophobic and a hydrophilicvinylic monomers. Suitable vinylic monomers include especially thosenormally used for the manufacture of contact lenses. A “hydrophilicvinylic monomer” refers to a monomer which as a homopolymer typicallyyields a polymer that is water-soluble or can absorb at least 10 percentby weight water.

The process according to the invention for molding a polymerizablematerial into ophthalmic devices, especially contact lenses, may takeplace in a manner known to a person skilled in the art, for example,photo-crosslinking of the polymerizable material in an appropriatecontact lens mold. Further examples of molded articles according to theinvention, apart from contact lenses, are e.g. intra-ocular lenses oreye dressings, furthermore biomedical articles which may be used insurgery, such as heart valves, artificial arteries or the like, alsofilms or membranes, e.g. membranes for diffusion control,photo-structurable films for data storage, or photo resist materials,e.g. membranes or molded articles for etch resist printing or screenresist printing.

In another further aspect, the present invention provides a method forproducing an ophthalmic device, the method comprising the steps of: a)introducing an aqueous solution of an above-described polymerizablematerial of the invention, in the presence or preferably in the absenceof one or more additional vinylic comonomers, and optionally in thepresence of a photo-initiator, into a mold; b) crosslinking by actinicradiation the polymerizable material, and c) opening the mold so thatthe ophthalmic device can be removed from the mold.

The polymerizable material solution may be introduced into a moldaccording to any suitable method known to a person skilled in the art,especially conventional dispensing, e.g. dropwise addition. If vinylicmonomers are present, the vinylic monomers are advantageously mixedfirst with the polymerizable material and then introduced into the mold.

Appropriate disposable molds are made, for example, from polypropylene.Suitable materials for re-usable moulds are e.g. quartz, sapphire glassor metals.

If the molded articles to be produced are contact lenses, these may beproduced in a manner known to a person skilled in the art, e.g. in aconventional “spin-casting mold”, as described for example in U.S. Pat.No. 3,408,429, or by the so-called full mold process in a static form,as described e.g. in U.S. Pat. Nos. 4,347,198, 5,508,317, 5,583,463,5,789,464, and 5,849,810.

Crosslinking may be initiated in the mold e.g. by means of actinicradiation, such as UV irradiation, ionizing radiation (e.g., gamma orX-ray irradiation).

As already mentioned, photo-crosslinking is advantageously carried outin the presence of a photo-initiator which can initiate radicalcrosslinking. The photo-initiator is advantageously added to theprepolymers according to the invention prior to introducing them intothe mold, preferably by mixing the polymers and the photo-initiatortogether. The amount of photo-initiator may be selected from a widerange, whereby an amount of up to 0.05 g/g polymer and especially up to0.003 g/g polymer has proved favorable.

What is notable is that the crosslinking according to the invention maybe effected in a very short time, e.g. in ≦60 minutes, advantageously in≦20 minutes, preferably in ≦10 minutes, most preferably in ≦5 minutes,particularly preferably in 1 to 60 seconds and most particularly in 1 to30 seconds.

What is also notable is that the contact lenses according to theinvention can be produced from a polymerizable material in a very simpleand efficient way compared with the prior art. Since the components of apolymerizable material can be purified prior to aqueous solutionpreparation, no subsequent purification, such as in particularcomplicated extraction of unpolymerized constituents is needed aftercrosslinking. In addition, since crosslinking is carried out in anessentially aqueous solution, a subsequent solvent exchange or thehydration step is not necessary. Finally, photo-polymerization iseffected within a short period.

Opening of the mold and removing of the molded article therefrom can becarried out according to any suitable methods known to a person skilledin the art.

Contact lenses obtained from a polymerizable material of the inventioncan have various advantageous properties which are possesed by contactlenses made from crosslinakble PVA. Exemplary properties include,without limitation, excellent compatibility with the human cornea, awell-balanced relationship between water content, oxygen permeabilityand good mechanical properties, high resistance to shape changes (evenafter autoclaving e.g. at about 120° C.). Furthermore, contact lensesobtained from a polymerizable material of the invention can also haveone or more improved physical properties including stress at break(N/mm²), percentage of elongation at break, toughness or energy to break(N·mm), and susceptibility to fracture.

In still a further aspect, the present invention provides a method formodifying one or more physical properties of a hydrogel article obtainedfrom the polymerization of a crosslinkable polymer, the methodcomprising the steps of: adding, into a solution of said crosslinkablepolymer, a modifier in an amount sufficient to modify said one or morephysical properties of said polymeric article, wherein said modifier isselected from the group consisting of nanoparticles having a hydrophilicsurface, a copolymer having hydrophobic groups or units for imparting atleast one desired physical property to said hydrogel article andhydrophilic groups or units in an amount sufficient to render itmiscible with the crosslinkable polymer, and mixtures thereof; mixingthoroughly said modifier and the crosslinkable polymer; and crosslinkingsaid crosslinkable polymer in the presence of the modifier to obtainsaid hydrogel article, wherein the one or more physical properties areselected from the group consisting of stress at break (N/mm²),percentage of elongation at break, toughness or energy to break (N·mm),and susceptibility to fracture.

The previous disclosure will enable one having ordinary skill in the artto practice the invention. In order to better enable the reader tounderstand specific embodiments and the advantages thereof, reference tothe following non-limiting examples is suggested. However, the followingexamples should not be read to limit the scope of the invention.

EXAMPLE 1

General Procedures

Susceptibility to fracture or Pin Hole Test are carried out as follows:Lenses are punctured with a −22 gauge needle, folded in half and thenrolled 2-3 times between fingers. If a lens does not fracture, it isgiven a “Pass” rating.

The water contents (%) of contact lenses are measured using an ATAGOCL-1 Refractometer or an ATAGO N2-E Refractometer.

Tensile properties (stress at break, elongation at break, modulus, andtoughness) are measured using MTS Tester or equivalent and load Cell 5N,Class 0.5 or equivalent, with a strain rate of 100 mm/minute.

Nelfilcon (CIBA Vision) is used in the following examples as awater-soluble crosslinkable polyvinyl alcohol to be blended with one ormore modifiers. Unless otherwise stated, an aqueous solution ofnelfilcon, containing 30% by weight of nelfilcon, 0.5% by weight ofPoloxamer 108, and 0.095% by weight of Irgacure 2959, is used toprepared a polymerizable material of the invention for making contactlenses.

Design of experiment and analysis of experimental results are performedby using Design-Expert, version, 6.0.0.

EXAMPLE 2

Vinyl pyrrolidone/vinyl acetate copolymers are obtained fromInternational Specialty Products. Copolymers with two different gradesare obtained. One grade is W-635 and has a molecular weight of about15,000 and is an aqueous solution containing 50% by weight of copolymer.The other grade is S-630 and has a molecular weight of about 51,000 andis a dry powder.

The above two vinyl pyrrolidone/vinyl acetate copolymers are blendedwith nelfilcon to prepare a series of samples for making contact lensesaccording to a D-Optimal crossed mixture design with 22 points. Thecomposition of each sample is listed in Table 1. Sample preparation isdescribed as follows. Nelfilcon aqueous solution (Example 1) is weighedin a capped vial. A vinyl pyrrolidone/vinyl acetate copolymer is weighedin another vial and then deionized water is added to the vial todissolve the copolymer. The copolymer solution is added to the nelfilconvial and mixed thoroughly. Both vinyl pyrrolidone/vinyl acetatecopolymers are soluble in all mixtures. The aqueous solution of thevinyl pyrrolidone/vinyl acetate copolymer is added to the nelfilcon andmixed. All solutions are clear.

Contact lenses are made from the above-prepared aqueous solution byusing plastic contact lens molds capable of casting a fully formedcontact lens. Poly(propylene) molds are filled with the appropriateamount of aqueous monomer solution. The molds containing the aqueoussolution are cured by UV irradiation (2.5 mW/cm²) for 10 seconds. Lensesare removed from the molds, placed in glass vials containing isotonicborate buffered saline (saline solution contained 0.005% Poloxamer) andthen sterilized. Lens properties are reported in Table 1.

Experimental results are analyzed using Design-Expert, version, 6.0.0.It is found that stress at break (SatB) and elongation at break (EatB)increase as the concentration of copolymer increases and the modulusdecreases as the concentration of the copolymer increases. The followingequations are obtained in terms of actual components.SatB=0.009451*(nelfilcon)−0.02778*(water)+0.015882*(copolymer)Modulus=0.00525*(nelfilcon)−0.00579*(water)−0.00319*(copolymer)EatB=2.242543*(nelfilcon)−4.11372*(water)+8.844298*(copolymer)

The SatB and EatB values at zero percent added copolymer are essentiallyfor the base control polymer and can be determined by substituting zerofor the appropriate terms in these equations. It can be seen that addingcopolymer with minimal water increases the values of these key polymerperformance indicators. TABLE 1 Stress Elong. At Sample NelfilconPolymer Water Copolymer At Break Modulus Beak No. (Wt. Fr.) (Wt. Fr.)(Wt. Fr.) Type (N/mm²) (N/mm²) (%) 1 0.8860 0.0102 0.1038 W-635 0.6070.390 132 2 0.8881 0.0102 0.1017 S-630 0.512 0.366 139 3 0.7212 0.09920.1796 W-635 0.274 0.220 158 4 0.7278 0.0989 0.1733 S-630 0.218 0.187169 5 0.7945 0.1017 0.1038 W-635 0.436 0.320 253 6 0.7998 0.0992 0.1010S-630 0.532 0.348 297 7 0.8144 0.0101 0.1755 W-635 0.380 0.316 168 80.8136 0.0101 0.1763 S-630 0.366 0.319 168 9 0.8339 0.0585 0.1076 W-6350.529 0.388 154 10 0.8431 0.0557 0.1012 S-630 0.890 0.364 258 11 0.78400.0767 0.1393 S-630 0.496 0.309 161 12 0.8517 0.0100 0.1383 W-635 0.4550.372 263 13 0.7687 0.0551 0.1762 W-635 0.344 0.324 96 14 0.8047 0.04790.1474 W-635 0.586 0.342 165 15 0.7580 0.0870 0.1550 W-635 0.618 0.289292 16 0.8480 0.0103 0.1417 S-630 0.225 0.346 60 17 0.7687 0.0551 0.1762S-630 0.324 0.301 113 18 0.7946 0.1026 0.1028 S-630 0.611 0.323 170 190.7242 0.1003 0.1755 S-630 0.400 0.290 158 20 0.8886 0.0100 0.1014 W-6350.803 0.477 208 21 0.7866 0.1059 0.1075 W-635 0.856 0.331 210 22 0.89000.0099 0.1001 S-630 0.280 0.372 104

EXAMPLE 3

Two grades, D1 and T5, of dextran are obtained from Amersham PharmaciaBiotech. D1 grade of dextran has a molecular weight of about 1000 and T5grade of dextran has a Molecular weight of about 5000.

The above two grades of dextran are blended with nelfilcon to prepare aseries of samples for making contact lenses according to a mixedD-Optimal mixture design with 17 points. The composition of each of thesamples is listed in Table 2. Sample preparation is the same asdescribed in Example 2. Some solutions (samples 6, 10, 11, and 17-19)are cloudy and the rest solutions are clear. TABLE 2 Composition (Wt.Fraction) Sample No. Nelfilcon Water Dextran Dextran type 1 0.88000.1091 0.0109 D1 2 0.8897 0.1003 0.0100 T5 3 0.7238 0.1772 0.0990 D1 40.7220 0.1771 0.1009 T5 5 0.7948 0.1034 0.1018 D1 6 0.7910 0.1045 0.1045T5 7 0.8111 0.1787 0.0102 D1 8 0.8105 0.1793 0.0102 T5 9 0.8432 0.10140.0554 D1 10 0.8404 0.1033 0.0563 T5 11 0.7828 0.1389 0.0783 T5 120.8506 0.1392 0.0102 D1 13 0.7402 0.1979 0.0619 D1 14 0.8077 0.13740.0549 D1 15 0.7607 0.1386 0.1007 D1 16 0.8530 0.1385 0.0085 T5 170.7661 0.1789 0.0550 T5 18 0.7912 0.1054 0.1034 T5 19 0.7218 0.18090.0973 T5 20 0.8860 0.1037 0.0103 D1 21 0.7884 0.1062 0.1054 D1 220.8875 0.1023 0.0102 T5

Contact lenses are prepared from the above-prepared aqueous solution inthe same manner as descried in example 2. Lenses are removed from themolds, placed in glass vials containing isotonic borate buffered saline(saline solution contained 0.005% poloxomer) and then sterilized. Lensproperties are reported in Table 3.

Experimental results are analyzed using Design-Expert, version, 6.0.0.Analysis of data indicates that physical properties of contact lensesmade from nelfilcon can be modified to some minor extent by blendingnelfilcon with dextran. TABLE 3 Stress at Elong. at Sample Lens ClarityBreak Break Modulus No. (Visual) (Measured) (N/mm²) (%) (N/mm²) 1 Clear0.20 0.243 87 0.288 2 Clear 0.28 0.303 82 0.344 3 Clear 0.10 0.115 600.099 4 Cloudy 25.77 0.192 67 0.165 5 Clear 0.10 0.177 78 0.152 6 Cloudy34.20 0.113 36 7 Clear 0.19 0.159 58 0.246 8 Clear 0.05 0.126 40 9 Clear0.16 0.340 113 0.261 10 Cloudy 34.60 0.268 83 0.197 11 Cloudy 34.100.055 24 12 Clear 0.33 0.383 144 0.234 13 Clear 0.52 0.359 154 0.227 14Clear 0.43 0.986 253 0.349 15 Clear 0.09 0.492 134 0.279 16 Clear 0.160.789 152 0.450 17 Cloudy 29.80 0.480 92 0.437 18 Cloudy 28.40 0.486 760.603 19 Cloudy 25.50 0.746 122 0.567 20 Clear 0.41 0.777 192 0.423 21Clear 0.27 0.488 107 0.382 22 Clear 1.23 0.691 132 0.465

EXAMPLE 4

Preparation of Vinyl Pyrrolidone/Acrylate Copolymers

Synthesis of Poly(NVP/GMA/MMA/BA). A 3-neck flask fitted with a balloon,paddle stirrer, gas inlet/outlet valves is charged N-vinylpyrolidone(NVP) (23.845 g), glycidylemethacrylate (GMA) (8.229 g), butylacrylate(BA) (4.041 g), methylmethacrylate (MMA) (2.252 g), vazo-52 (0.2051 g)and 325 mL of toluene. The flask is filled with nitrogen until theattached 9 inch capacity balloon on the reaction flask is filled. Vacuumis then applied until the balloon collapsed and the reaction mixturejust began to bubble. This operation is repeated about five times andthen the reaction mixture is blanketed with nitrogen. The reactionmixture is heated at 55° C. under nitrogen for about 20 hours.Approximately 0.5 mL of reaction mixture is poured into about 10 mL ofhexanes and about 20 mg of the resulting precipitate is dissolved inchloroform and then cast onto a NaCl disk. The resulting film is driedat about 60° C. for 5 minutes and then analyzed by FT-IR. Selectedpeaks: 2957, 2929, 2873, 1729, 1685, 1460, 1423, 1285, 1270, 1170, 994cm⁻¹.

Conversion of Poly(NVP/GMA/MMA/BA) to a Photo-Curable Copolymer.Approximately 350 mL of toluene solution containing a calculated 35grams of the obtained poly(DMA/GMA/BEA/MMA) is combined with DABCO(2.166 grams), 4-methoxyphenol (0.518 grams), and 350 mL of toluene. Thereaction mixture is then heated to about 65° C. and then methacrylicacid (48/10 g) is added. The reaction mixture is then heated to about80° C. for about 30 hours. The resulting photo-curable copolymer isisolated by pouring the reaction mixture into about 1500 mL of hexanes.The precipitated copolymer is dissolved in THF and reprecipitated inhexanes and then dried for a few days in a vacuum oven. Approximately 20mg of sample is dissolved in about 0.5 mL of chloroform and then a filmis cast onto a NaCl disk. The film is dried at about 50° C. f or 10minutes. FT-IR analysis showed characteristic ester and amide CO peaksnear 1726 and 1643 cm⁻¹ respectively. In addition, FT-IR showed a broadOH peak near 3342, and a peak characteristic of C═C near 1566 cm⁻¹.

The vinyl-substituted vinyl pyrrolidone/acrylate copolymers are blendedwith nelfilcon to prepare a series of samples for making contact lensesaccording to a D-Optimal mixture design with 14 points. The compositionof each of the samples is listed in Table 4. Sample preparation isdescribed as follows. Nelfilcon aqueous solution is weighed in a cappedvial. A vinyl-substituted vinyl pyrrolidone/acrylate copolymer isweighed in another vial and then deionized water is added in the vial todissolve the copolymer. The copolymer solution is added to the nelfilconvial and mixed thoroughly. All solutions are clear except for the browncolor imparted by the vinyl-substituted vinyl pyrrolidone/acrylatecopolymer. TABLE 4 Composition (Wt. Fraction) Sample No. Nelfilcon WaterNVP copolymer 1 0.5039 0.2992 0.1969 2 0.3007 0.4998 0.1995 3 0.48520.3931 0.1217 4 0.5500 0.4001 0.0499 5 0.4552 0.4953 0.0495 6 0.65140.2991 0.0495 7 0.4090 0.4353 0.1557 8 0.5748 0.3002 0.1250 9 0.53170.3463 0.1220 10 0.4124 0.3923 0.1953 11 0.4500 0.4996 0.0504 12 0.36420.4552 0.1806 13 0.5018 0.2997 0.1985 14 0.6521 0.2987 0.0492

Contact lenses are prepared from the above-prepared aqueous solution bymethods described in Example 2. Lenses are removed from the molds,placed in glass vials containing isotonic borate buffered saline (salinesolution contained 0.005% poloxomer) and then sterilized. Lensproperties are reported in Table 5. TABLE 5 Stress at Max. Break BreakModulus Elong. At Stress. Max. Elong. Lens Sample No. (N/mm²) (N/mm²)Break (%) (N/mm²) At Break (%) Clarity¹ 1 1.931 1.391 135 2.533 172 2 20.558 0.915 62 0.992 90 3 3 1.297 0.904 172 2.309 226 2 4 0.173 37 0.24963 1 5 0.259 0.244 81 0.370 118 1 6 0.370 0.535 72 0.643 131 1 7 0.9060.676 102 1.675 179 2 8 1.671 0.927 149 2.895 182 1 9 1.461 0.988 1252.439 190 2 10 0.948 1.069 83 1.421 120 2 11 0.167 48 0.219 59 1 121.279 0.981 121 1.706 157 3 13 2.010 1.327 140 2.800 190 3 14 0.8040.627 114 1.881 246 1¹subjective scale: 1 = clear; 2 = slight haze; 3 = hazy

Experimental results are analyzed using Design-Expert, version, 6.0.0.It is found that stress at break (SatB), elongation at break (EatB), andmodulus increase as the concentration of copolymer increases. Lensclarity improves as the amount of vinyl-substituted vinylpyrrolidone/acrylate copolymer decreases. This is probably due to thefact that vinyl pyrrolidone is not purified before makingvinyl-substituted vinyl pyrrolidone/acrylate copolymer and thevinyl-substituted vinyl pyrrolidone/acrylate copolymer is brown incolor. The following equations are obtained in terms of actualcomponents:SatB=−0.001012*A−0.00381423*B+0.015882*C+0.00298 A*CModulus=0.009907*A−0.010313*B−0.057295*CEatB=1.588316*A−66.03316*B−4.128813*Cwherein A, B, and C are nelfilcon, water, and copolymer respectively.The lens properties with pure nelfilcon can be calculated bysubstituting zero in the equations for water and copolymer. It can beseen that SatB increases as the water and copolymer are added to themonomer mixture.

EXAMPLE 5

Nano-size silica fillers (particles), Aerosil 0×50 and Aerosil 200, aresupplied by Degussa. Aerosil 0×50 has an averaged particle size of about40 nm and Aerosil 200 has an averaged particle size of about 12 nm.

A series of samples is prepared as follows. Nelfilcon aqueous solutionis weighed in a capped vial. Nano-size silica fillers are weighed inanother vial and then weighed amount of nelfilcon is added. The mixtureis stirred and centrifuged at 4000 rpm for 15 minutes. The compositionof each of the samples is listed in Table 6. TABLE 6 Composition (Wt.Fraction) Sample Nel- Aerosil Aerosil Observations after No. filcon 2000X50 centfifuging * 1 0.9502 0.0498 Large amount of precipitate 2 0.90010.0999 Too thick to centrifuge 3 0.9317 0.0683 Large amount ofprecipitate 4 0.9010 0.0990 Large amount of precipitate 5 1.0000 60.9974 0.0026 No precipitate 7 0.9946 0.0054 Very small precipitate 80.9984 0.0016 Very small precipitate 9 0.9953 0.0047 Very smallprecipitate* 15 minutes at 4000 rpm

Contact lenses are prepared from the above-prepared aqueous solutionsfrom sample Nos. 5-9 using methods described in Example 2 except thatthe UV irradiance used here is 1.9 mWcm⁻². Lens properties are reportedin Table 7. Lens physical properties such as stress at break, elongationat break increase with the addition of fillers. Lens modulus appears tobe independent of the presence of fillers. Susceptibility to fracture(or Pin Hole Test) can be improved by blending fillers with nelfilcon.TABLE 7 Stress Elong. Max. Max. at At Stress Elong. Pin Sample BreakModulus Break at Break At Break Hole No. (N/mm²) (N/mm²) (%) (N/mm²) (%)Test* 5 1.778 0.789 206 2.423 424 1 (1.146) (0.094) (130) 6 2.319 0.815343 2.623 393 4 (2.623) (0.052)  (74) 7 2.958 0.809 345 3.974 404 4(0.706) (0.085)  (42) 8 2.047 0.783 337 2.255 460 4 (0.255) (0.075) (76) 9 1.714 0.847 212 2.670 372 4 (2.217) (0.034) (128)Numbers in the parenthesis are standard deviations*Pin Hole Test is performed after autoclaving by puncturing lens centerwith a needle and folding it over on itself; 1 = fail, 5 = pass.

EXAMPLE 6

Two copolymers, GANEX P-904LC and GAFFIX VC-713, are supplied byInternational Specialty Products. GANEX P-904LC is an aqueous solutioncontaining 30% (w/w) of a copolymer of N-vinyl pyrrolidone (90%) and theC₄ α olefin 1-butene (10%). GAFFIX VC-713 is a solution (in ethanol)containing 70% (w/w) of a copolymer of N-vinyl pyrrolidone, N-vinylcaprolactone, and dimethylaminoethyl methacrylate.

The above two copolymers are blended with nelfilcon to prepare a seriesof samples for making contact lenses. The composition of each of thesamples is listed in Table 8. Sample preparation is described asfollows. Nelfilcon aqueous solution is weighed in a capped vial. Acopolymer is weighed in another vial and then added to the nelfilconvial and mixed thoroughly. TABLE 8 Sample No. Nelfilcon P904LC * VC-7131156-95- (Wt. Fr.) (Wt. Fr.) (Wt. Fr.) 1 0.9533 0.0467 2 0.9012 0.0988 30.8505 0.1495 4 0.9504 0.0496 5 0.8999 0.1001 6 0.8510 0.1490 Control*1.0000Focus Dailies lot 1158643

Contact lenses are prepared from the above-prepared aqueous solution bymethods described in Example 2 except the monomer solution is irradiatedwith UV radiation at 2.5 mWcm⁻². Lenses are removed from the molds andplaced in glass vials containing isotonic borate buffered saline (salinesolution contained 0.005% poloxomer) and then sterilized by autoclave.

Lens properties are reported in Table 9. Lens modulus decreases withincreasing concentration of copolymer (VC-713 or P904-LC). The energy tobreak (toughness) of all lenses made from the blends is increasedsignificantly over those of control lenses. Other physical properties(such as peak stress and elongation at break) of lenses made from theblends are statistically significantly better than those of controllenses. TABLE 9 Elongation Energy to Center Peak Stress Modulus At BreakBreak Diameter Thickness Sample No. (N/mm²) (N/mm²) % (N*mm) (mm) (mm) 11.439 0.531 474 17.596 13.95 0.185 2 1.485 0.443 424 14.327 14.00 0.1823 1.424 0.391 471 14.893 13.91 0.179 4 1.766 0.513 386 14.575 13.970.182 5 1.719 0.451 369 12.947 14.01 0.180 6 2.053 0.456 386 15.15014.02 0.180 Control 0.563 0.313 304 4.819 13.80 0.200Control is 100% nelfilcon lens

EXAMPLE 7

A copolymer, GANEX P-904LC, is supplied by International SpecialtyProducts. GANEX P-904LC is an aqueous solution containing 30% (w/w) of acopolymer of N-vinyl pyrrolidone (90%) and the C₄ α olefin 1-butene(10%).

The compositions of the samples are listed in Table 10 and are preparedas described in Example 6. TABLE 10 Composition (Wt. Fraction) SampleNo. Nelfilcon P-904LC 1 0.8499 0.1501 2 0.9484 0.0516 3 0.8995 0.1005 40.8475 0.1525 Control*Focus Dailies, lot 2064670, target power = −3.00

Contact lenses are prepared from the polymerizable compositions. Lensesare prepared by methods described in Example 2. Monomer in the moldscontaining the aqueous solution is cured by UV irradiation (2.2 mW/cm²)(for a total of 9 seconds). Mold halves containing lenses are placed indeionized water to soak for several seconds and then lenses are removedfrom the molds and placed in glass vials containing isotonic boratebuffered saline (saline solution contained 0.005% poloxomer) and thensterilized by autoclave.

Extraction studies are carried out as follows. Each lens is placed in2.6 g of buffered saline and autoclaved. The saline in which the lensesare autoclaved is tested for NVP/1-butene copolymer. In a separateexperiment, the lenses are extracted in saline and then the saline istested for the presence of the NVP/1-butene copolymer. The limit ofdetection is 50 ppm. It is found that NVP/1-butene copolymer is notextracted from the lenses either in the autoclave or in a separatesaline extraction experiment.

Lens properties are reported in Table II. The data in Table II indicatethat the NVP/1-butene copolymer improves the physical properties (peakstress, elongation at break and toughness of Focus Dailies lenses. Itappears that the presence of the hydrophobic component (1-butene) mayplay an important role in improving physical properties of lenses. It isalso technologically meaningful that the blended copolymer does notextract from the nelfilcon even though there is no apparent chemicalbonding of the nelfilcon with the copolymer. TABLE 11 Peak Elong. AtCenter Stress Modulus Toughness Break Diameter Thickness Water SampleNo. (N/mm²) (N/mm²) (N*mm) (%) (mm) (mm) (%) 1 1.096 0.406 12.025 39113.79 0.210 2 70.3 3 74.1 4 76.9 Control* 0.835 0.486 5.847 251 13.800.200 70.0

EXAMPLE 8

Preparation of DMA Copolymer: Poly(DMA/GMA/BEA/MMA)

Vinyl-substituted Poly(DMA) is prepared by polymerizingN,N-dimethylacrylamide (DMA) with glycidyl methacrylate (GMA), methylmethacrylate (MMA), and 2-butoxyethylateacrylate (BEA). A 3-neck flaskfitted with a balloon, paddle stirrer, gas inlet/outlet valves ischarged DMA (23.845 g), GMA (8.036 g), BEA (6.031 g), MMA (2.029 g),vazo-52 (0.2041 g) and 325 mL of toluene. The flask is filled withnitrogen until the attached 9 inch capacity balloon on the reactionflask is filled. Vacuum is then applied until the balloon collapsed andthe reaction mixture just began to bubble. This operation is repeatedabout five times and then the reaction mixture is blanketed withnitrogen. The reaction mixture is heated at 55° C. under nitrogen forabout 20 hours. The reaction mixture volume is then adjusted to 400 mLby the addition of toluene and then approximately 50 mL of the reactionmixture is poured into 150 mL of hexanes. The resulting precipitate ofPoly(DMA/GMA/BEA/MMA) is dried under vacuum at about 35-40° C. for aboutone day. About 20 mg of the dried sample is dissolved in about 0.5 mL ofchloroform, cast onto a NaCl disk, and dried at about 50° C. for about10 minutes and then analyzed by FT-IR. Selected peaks: 2932, 2871, 1728,1642, 1496, 1398, 1355, 1257, 1134, 993 cm⁻¹.

Conversion of Poly(DMA/GMA/BEA/MMA) to a Photo-Curable Copolymer

Approximately 350 mL of toluene solution containing a calculated 35grams of the obtained poly(DMA/GMA/BEA/MMA) is combined with DABCO (2.11grams), 4-methoxyphenol (0.509 grams), and 850 mL of toluene. Thereaction mixture is then heated to about 65° C. and then methacrylicacid (48.1 g) is added. The reaction mixture is then heated to about 80°C. for about 30 hours. The resulting photo-curable copolymer is isolatedby pouring the reaction mixture into about 1500 mL of hexanes. Theprecipitated copolymer is dissolved in THF and reprecipitated in hexanesand then dried for a few days in a vacuum oven. Approximately 20 mg ofsample is dissolved in about 0.5 mL of chloroform and then a film iscast onto a NaCl disk. The film is dried at about 50° C. f or 10minutes. FT-IR analysis showed characteristic ester and amide CO peaksnear 1726 and 1643 cm⁻¹ respectively. In addition, FT-IR showed a broadOH peak near 3350, and a peak characteristic of C═C near 1510 cm⁻¹ A 30weight percent solution of the copolymer in water containing 0.033weight percent Irgacure 2959 had viscosity of 588 cps at 25° C. Contactlenses with water content of about 79 percent are obtained byphoto-curing this solution at about 2.5 mW/cm² for 20 seconds.

Lens Preparation

The above obtained vinyl-substituted DMA copolymer is blended withnelfilcon to prepare a series of samples for making contact lensesaccording to a D-Optimal crossed mixture design with 14 points. Thecomposition of each of samples is listed in Table 12. Sample preparationis described as follows. Nelfilcon aqueous solution is weighed in acapped vial. The vinyl-subsituted DMA copolymer is weighed in anothervial and then deionized water is added in the vial to dissolve the DMAcopolymer. The DMA copolymer solution is added to the nelficon vial andmixed thoroughly. A clear aqueous solution is obtained.

Contact lenses are prepared from the above-prepared aqueous solutionaccording to procedures given in Example 2 except that the monomersolutions are irradiated with UV radiation at 2.5 mWcm⁻². Lenses areremoved from the molds, placed in glass vials containing isotonic boratebuffered saline (saline solution contained 0.005% poloxomer) and thensterilized.

Lens properties are reported in Table 12. It appears that there is nostatistically significant model that can be used to interpret theresults. The DMA copolymer appears to influence lens properties but notin a predictable manner. Some formulations (e.g., 1, 5, and 8) can beused to prepare lenses which have very good tensile properties and canpass a pin hole test. TABLE 12 Sample Composition (weigh fraction) SatBModulus Pin Hole No. Nelfilcon Copolymer water (N/mm²) (N/mm²) EatB (%)Test* 1 0.8083 0.1826 0.0091 0.642 0.369 233 2 2 0.8839 0.1056 0.01050.451 0.381 168 2 3 0.7909 0.1531 0.0560 0.606 0.396 133 1 4 0.79830.1239 0.0778 0.542 0.283 109 1 5 0.7895 0.1078 0.1027 1.267 0.329 212 26 0.7015 0.2024 0.0961 1 7 0.8361 0.1537 0.0102 0.311 0.388 76 2 80.8287 0.1119 0.0594 1.062 0.568 272 2 9 0.7345 0.2089 0.0566 0.1950.269 65 1 10 0.8165 0.1277 0.0558 0.355 0.431 86 2 11 0.7865 0.20340.0101 0.590 0.414 157 1 12 0.7899 0.1068 0.1033 0.159 40 2 13 0.69570.2039 0.1004 14 0.8918 0.0984 0.0098 0.691 0.466 126 2*1 = broke; 2 = not broke

EXAMPLE 9

Preparation of Isocyanate-Capped Poly(urethane)

Isocyanate-capped poly(urethane) A is prepared as follows. PEG-1000(861.30 grams) and TMP (21.67 grams) are combined and heated at 75° C.The resulting melt is dried over 85 grams of 3 angstrom molecular sievesfor about 24 hours at 60° C. IPDI (316.90 grams) is mixed with to thePEG/TMP melt and the resulting mixture is heated at 60° C. for about onehour. The reaction mixture is then decanted away from the melt andstirred at 75° C. under nitrogen until the percentage of NCO in theprepolymer is about 2.12% by weight. The total reaction time is about159 hours.

Isocyanate-capped poly(urethane) B is prepared as follows. To a 60° C. Amelt consisting of PEG-1000 (701.20 grams), Pluronic 17R₂ (78.46 grams)and TMP (24.77 grams) is added 80 grams of activated molecular sieves (3angstrom). To the 60° C. melt is added IPDI (287.16 grams) and themixture is stirred at 75° C. under nitrogen until the percentage of NCOin the prepolymer is about 2.0% by weight. The total reaction time isabout 98 hours. A 30 weight percent solution of this sample in water hada viscosity of 2670 cps.

Preparation of Photocurable Poly(Urethane) Prepolymer

The above NCO terminated poly(urethane) (polyurethane prepolymer) A andB are converted to a TBAM capped poly(urethane) A and B in approximately200 gram portions in 1-liter plastic beakers. To each sample ofpoly(urethane) is added a calculated 1-equivalent of TBAM. Samples aremixed thoroughly using plastic rods and then checked by FT-IR.Additional TBAM is added dropwise until NCO is consumed. Aqueoussolutions containing about 30 percent by weight of poly(urethane) areprepared by diluting TBAM capped poly(urethane) samples with de-ionizedwater containing 0.05% by weight of Irgacure 2959.

Lens Preparation

The above two polyurethane prepolymers, A and B, are blended withnelfilcon to form a series of samples for making contact lenses undervarious irradiation conditions. The composition of each of the samplesis listed in Table 13. Sample preparation is described as follows.Nelfilcon aqueous solution is weighed in a capped vial. The polyurethaneprepolymer is weighed in another vial and then added to the nelficonvial and mixed thoroughly. A clear aqueous solution is obtained. TABLE13 Half Composition (Wt. Fraction) Curing UV Sample Polyurethaneprepolymer Time Intensity No. Nelfilcon A B (sec) (mW/cm²) 1 0.85010.1499 6.50 2.26 2 0.8499 0.1501 6.50 2.26 3 0.9437 0.0563 6.50 2.26 40.9438 0.0562 6.50 2.26 5 0.8501 0.1499 4.15 2.26 6 0.8499 0.1501 4.152.26 7 0.9437 0.0563 4.15 2.26 8 0.9438 0.0562 4.15 2.26 9 0.8501 0.14996.50 1.67 10 0.8499 0.1501 6.50 1.67 11 0.9437 0.0563 6.50 1.67 120.9438 0.0562 6.50 1.67 13 0.8501 0.1499 4.15 1.67 14 0.8499 0.1501 4.151.67 15 0.9437 0.0563 4.15 1.67 16 0.9438 0.0562 4.15 1.67 17 0.90040.0996 5.17 1.93 18 0.8992 0.1008 5.17 1.93

Contact lenses are prepared from the above-prepared samples. Usingmethods described in Example 2. The monomer mixture in the moldscontaining the sample is cured by a UV lamp for times and intensitieslisted in Table 13. Casting mold halves containing lenses are firstplaced in deionized water to soak for several seconds and then lensesare removed from the mold halves. Lenses are placed in glass vialscontaining isotonic borate buffered saline solution contained 0.005%poloxomer) and then autoclaved prior to measuring physical properties.Lens properties are reported in Table 14.

Lens clarity of lenses generally decreases as the polyurethane levelincreases. This effect is larger at the higher polyurethane level forthe higher curing times for those lenses made from a blend of prepolymerA and nelfilcon.

Peak stress of lenses made from a blend of nelfilcon and prepolymer Aincreases slightly as the curing time increases for the lower UVintensity but is relatively constant for the high UV intensity. At thelow curing time, peak stress of lenses made from a blend of nelfilconand prepolymer B increases as the UV intensity decreases and as thepolyurethane level decreases. The situation reverses at the high curingtime.

Elongation at break of lenses made from a blend of nelfilcon andprepolymer A increases as the polyurethane level decreases at the low UVintensity and increases at the high polyurethane level at the high UVintensity. Elongation at break of lenses made from a blend of nelfilconand prepolymer B increases as the polyurethane level decreases and asthe UV intensity increases for the low cure time. The situation with thehigh curing time reverses for the polyurethane level at the low UVintensity and increases at the high polyurethane level at the high UVintensity.

Modulus of lenses decreases as the polyurethane level increases. Theeffect is greater at the high UV intensity at the higher polyurethanelevel. Energy to break (toughness) increases as the polyurethane leveldecreases at the low UV intensity. Energy to break (toughness) increasesas the polyurethane level decreases at the low curing time. The reverseis true at the high curing time. TABLE 14 Center Peak Elongation Energyto Lens Diameter Thickness Stress at Break Modulus Break Sample No.Clarity^(a) (mm) (mm) (N/mm²) (%) (N/mm²) (N*mm) 1 3 13.98 0.267 1.418562 0.356 17.425 2 3 13.93 0.274 2.312 442 0.356 14.482 3 1 13.85 0.2631.560 371 0.367 14.344 4 1 13.83 0.269 1.375 421 0.399 18.688 5 2 13.960.268 1.205 385 0.376 15.701 6 2 14.01 0.264 1.268 379 0.344 11.004 7 113.86 0.272 1.430 368 0.415 16.335 8 1 13.89 0.268 1.501 398 0.37017.719 9 3 13.96 0.270 0.972 288 0.325 8.575 10 3 13.96 0.270 1.374 3940.324 15.428 11 1 13.91 0.269 1.366 428 0.398 19.492 12 1 13.91 0.2771.117 338 0.377 12.422 13 2 14.00 0.272 1.608 274 0.311 6.756 14 2 14.000.268 0.950 297 0.293 7.738 15 1.5 14.03 0.278 1.272 424 0.382 19.409 161.5 14.05 0.267 1.819 451 0.395 22.700 17 1.5 13.99 0.272 1.594 3920.382 18.989 18 1.5 14.05 0.275 1.410 329 0.372 13.401 Control^(b) 13.800.266 0.370 276 0.276 3.402^(a)Visual clarity scale: 1 = clear; 5 = hazy^(b)Focus Dailies lenses (−1.00 D)

EXAMPLE 10

Polyurethane prepolymers A and B are prepared as described in Example 9.The polyurethane prepolymers A and B are blended with nelfilcon to forma series of samples for making contact lenses under various curing timeconditions. The composition of each of the samples is listed in Table15. Samples are prepared as described in Example 9. TABLE 15 Composition(Wt. Fraction) Sample Polyurethane Polyurethane Half Cure Time No.Nelfilcon prepolymer A prepolymer B (second) 1 0.8999 0.1001^(a) 4 20.8996 0.1004^(b) 4 3 0.9498 0.0502^(a) 4 4 0.9499 0.0501^(b) 4 5 0.89990.1001^(a) 3 6 0.8996 0.1004^(b) 3 7 0.9498 0.0502^(a) 3 8 0.94990.0501^(b) 3 9 0.9249 0.0751^(a) 3.5 10 0.9249 0.0751^(b) 3.5

Contact lenses are prepared from the above-prepared samples usingmethods described in Example 2. The UV irradiation is t 2 mWcm⁻² fortimes listed in Table 2. Lenses are placed in glass vials containingisotonic borate buffered saline (saline solution contained 0.005%poloxomer) and then autoclaved prior to measuring physical properties.

Lens properties are reported in Table 16. All lenses made from a blendof nelfilcon have values of elongation at break and energy to break muchgreater than those control lenses. TABLE 16 Center Peak Elongation atEnergy to Sample Diameter Thickness Stress Break Modulus Break No.Clarity^(a) (mm) (mm) (N/mm²) (%) (N/mm²) (N*mm) 1 1.5 13.84 0.272 1.159369 0.519 16.223 2 1.5 13.90 0.274 0.698 267 0.495 4.443 3 1 13.74 0.2721.486 361 0.597 18.659 4 1 14.00 0.264 0.896 237 0.455 6.147 5 2 13.960.266 1.166 344 0.418 14.158 6 2 13.78 0.266 1.288 319 0.444 12.884 7 113.76 0.272 0.896 246 0.456 7.664 8 1 13.89 0.261 1.044 285 0.446 9.6089 1 13.82 0.268 1.453 224 0.576 9.230 10 1 13.98 0.274 1.682 294 0.54815.488 Control^(b) 13.80 0.226 0.436 175 0.378 2.680^(a)Visual clarity scale: 1 = clear; 5 = hazy^(b)Focus Dailies lenses, power −1.00 D

EXAMPLE 11

Preparation of vinyl-substituted DMA copolymer. Vinyl-substituted DMAcopolymer is prepared as described in Example 8.

Preparation of polyurethane prepolymer. NCO terminated poly(urethane) isprepared as follows. PEG-1000 (962.6 grams), TMP (32.28 grams), and IPDI(222.3 grams) are combined in a round flask which is equipped with a gasinlet valve and a paddle stirring device. The flask is placed in apreheated 75° C. oil bath and nitrogen is passed through the reactionvessel for several minutes. The reaction mixture is then heated undernitrogen at about 75° C. for about 107 hours. The conversion of NCO ismonitored by titration.

The above NCO terminated poly(urethane) is converted to TBAM cappedpoly(urethane) in approximately 200 gram portions in 1-liter plasticbeakers. To each sample of poly(urethane) is added a calculated1-equivalent of TBAM. Samples are mixed thoroughly using plastic rodsand then checked by FT-IR. Additional TBAM is added dropwise until NCOis consumed. Aqueous solutions containing about 30 weight percentpoly(urethane) and 0.05 weight percent Irgacure 2959 are prepared byadding de-ionized water and Irgacure 2959 into each sample.

The above DMA copolymer and polyurethane prepolymer are blended withnelfilcon to form a series of samples (Table 17) for making contactlenses according to a D-Optimal crossed mixture design with 14 points.The results show, upon regression analysis, that break stress over thatexpected for pure nelfilcon increases as the amount of DMA andpolyurethane copolymers increase. The same is true for elongation atbreak. TABLE 17 Composition (Wt. Fraction) Polyurethane Sample No.Nelfilcon DMA copolymer prepolymer 1 0.8525 0.0985 0.0490 2 0.89580.0580 0.0462 3 0.8869 0.0693 0.0438 4 0.9289 0.0553 0.0158 5 0.87980.1079 0.0123 6 0.9400 0.0413 0.0187 7 0.8798 0.0827 0.0375 8 0.92490.0484 0.0267 9 0.9109 0.0558 0.0333 10 0.8731 0.0976 0.0293 11 0.88150.1067 0.0118 12 0.8995 0.0497 0.0508 13 0.8481 0.1019 0.0500 14 0.96800.0185 0.0135

Nelfilcon aqueous solution is weighed in a capped vial. The polyurethaneprepolymer and DMA copolymer are weighed in separated vials and thensufficient deionized water is added to make 30% by weight solutions. TheDMA copolymer aqueous solution and the polyurethane prepolymer aqueoussolution are added to the nelficon vial and mixed thoroughly. Allsolutions are hazy but all lenses are clear.

Contact lenses are prepared from the above-prepared sample using methodslisted in Example 2. Monomer mixtures are irradiated at about 2.2 mWcm⁻²for about 10 seconds. Lenses are removed from the molds, placed in glassvials containing isotonic borate buffered saline (saline solutioncontained 0.005% poloxomer) and then sterilized. Lens properties arereported in Table 18. TABLE 17 Elongation At Max. Break Max. ElongationStress at Break Modulus Break Stress at Break Sample No. (N/mm²) (N/mm²)(%) (N/mm²) (%) 1 1.116 0.647 290 1.784 330 2 1.211 0.769 330 2.191 3473 1.378 0.780 248 2.280 383 4 0.780 0.868 119 1.994 351 5 1.536 0.803224 2.207 378 6 1.080 0.749 217 1.778 404 7 0.622 0.579 110 2.014 239 81.833 0.884 221 2.058 361 9 1.468 0.899 217 1.908 342 10 1.790 0.766 2512.414 349 11 2.227 0.679 273 4.493 373 12 1.292 0.943 192 2.014 347 131.568 0.718 277 2.230 378 14 1.535 0.920 271 2.037 385

EXAMPLE 12

Preparation of vinyl-substituted DMA copolymer. Vinyl-substituted DMAcopolymer is Prepared as follows.

A 3-neck flask fitted with a balloon, paddle stirrer, gas inlet/outletvalves is charged DMA (23.812 g), GMA (8.079 g), BEA (2.021 g), MMA(6.100 g), vazo-52 (0.2145 g) and 225 mL of toluene. The flask is filledwith nitrogen until the attached 9 inch capacity balloon on the reactionflask is filled. Vacuum is then applied until the balloon collapsed andthe reaction mixture just began to bubble. This operation is repeatedabout five times and then the reaction mixture is blanketed withnitrogen. The reaction mixture is heated at 55° C. under nitrogen forabout 20 hours. The poly(DMA/GMA/BEA/MMA) is precipitated by pouring thetoluene solution into 1500 mL of hexanes. The copolymer is thendissolved in about 750 mL of toluene and converted to photo-curablecopolymer as described below.

Conversion of Poly(DMA/GMA/BEA/MMA) to a Photo-Curable Copolymer

Approximately 700 mL of toluene solution containing a calculated 35grams of the obtained poly(DMA/GMA/BEA/MMA) is combined with DABCO(1.172 grams), 4-methoxyphenol (0.209 grams), and 500 mL of toluene. Thereaction mixture is then heated to about 65° C. and then methacrylicacid (24.36 g) is added. The reaction mixture is then heated to about80° C. for about 30 hours. The resulting photo-curable copolymer isisolated by pouring the reaction mixture into about 1000 mL of hexanesand dried in a vacuum oven at about 30° C. for a few hours. Thephoto-curable copolymer is then dissolved in THF and reprecipitated inabout 1 liter of hexanes. The precipitated copolymer is dissolved in THFand re-precipitated in hexanes and then dried for a few days in a vacuumoven. Approximately 20 mg of sample is dissolved in about 0.5 mL ofchloroform and then a film is cast onto a NaCl disk. The film is driedat about 50° C. f or 10 minutes. FT-IR analysis showed characteristicester and amide CO peaks near 1726 and 1643 cm⁻¹ respectively.

A 30 weight percent solution of the copolymer in water containing 0.033weight percent Irgacure 2959 had viscosity of 1270 cps at 25° C. Contactlenses with water content of about 74 percent are obtained byphoto-curing this solution at about 2.5 mW/cm² for 20 seconds.

Preparation of polyurethane prepolymer. NCO terminated poly(urethane) isprepared as follows. PEG-1000 is dried over 3A molecular sieves at 65°C. for about 4 days prior to use. A ratio of sieves to PEG is about1:10. PEG-1000 (962.6 grams), TMP (32.28 grams), and IPDI (222.3 grams)are combined in a round flask that is equipped with a gas inlet valveand a paddle-stirring device. The flask is placed in a preheated 75° C.oil bath and nitrogen is passed through the reaction vessel for severalminutes. The reaction mixture is then heated under nitrogen at about 75°C. for about 107 hours. The conversion of NCO is monitored by titration.

The above NCO terminated poly(urethane) is converted to TBAM cappedpoly(urethane) in approximately 200 gram portions in 1-liter plasticbeakers. To each sample of poly(urethane) is added a calculated1-equivalent of TBAM. Samples are mixed thoroughly using plastic rodsand then checked by FT-IR. Additional TBAM is added dropwise until NCOis consumed. Aqueous solutions containing about 30 weight percentpoly(urethane) and 0.05 weight percent Irgacure 2959 are prepared byadding de-ionized water and Irgacure 2959 into each sample.

The above DMA copolymer and polyurethane prepolymer are blended withnelfilcon to form a series of samples (Table 19) for making contactlenses. TABLE 19 Composition (Wt. Fraction) Polyurethane DMA DMAcopolymer Sample No. Nelfilcon prepolymer copolymer type 1 0.8388 0.10880.0524 1310-2 2 0.7945 0.1010 0.1045 1297-90 3 0.7936 0.1032 0.10321310-2 4 0.8513 0.0506 0.0981 1310-2 5 0.8452 0.0524 0.1024 1297-90 60.8421 0.1039 0.0540 1297-90 7 0.8961 0.1039 8 0.8942 0.0590 0.04681297-90 9 0.9043 0.0957 1297-90 10 0.9032 0.0968 1310-2 11 0.8949 0.05350.0516 1310-2 12 0.8907 0.1093 13 0.8339 0.0822 0.0839 1297-90 14 0.83580.0829 0.0813 1310-2 15 0.8619 0.0711 0.0670 1297-90 16 0.8668 0.06800.0652 1310-2 17 0.8656 0.0946 0.0398 1297-90 18 0.8933 0.1067 19 0.89770.1023 1310-2 20 0.8994 0.1006 1297-90 21 0.7992 0.0997 0.1011 1310-2 220.8928 0.1072

Nelfilcon aqueous solution is weighed in a capped vial. The polyurethaneprepolymer and DMA copolymer are weighed in separated vials and thensufficient deionized water is added to make 30% by weight solutions. TheDMA copolymer aqueous solution and the polyurethane prepolymer aqueoussolution are added to the nelficon vial and mixed thoroughly.

Contact lenses are prepared from the above-prepared samples usingmethods described in Example 2. Monomer solutions are irradiated atabout 2.2 mWcm⁻² for about 10 seconds. Lenses are removed from themolds, placed in glass vials containing isotonic borate buffered saline(saline solution contained 0.005% poloxomer) and then sterilized. Lensproperties are reported in Table 20. The regression analysis shows thatthe break stress increases as the concentration of the urethane and DMAcopolymer increases. This indicates that properties of pure nelfilconhave been improved by the addition of these components. TABLE 20 Stressat Break Elongation at Break (N/mm²) (%) Modulus Pin Hole Lens SampleNo. Average Maximum Average Maximum (N/mm²) Test¹ Clarity² 1 1 1 1 1 1 11 2 1.006 1.479 125 146 0.761 3 1 3 2 1 4 5 1.655 3.101 199 345 0.793 41 6 0.986 1.561 149 260 0.792 4 1 7 2.181 2.181 284 284 0.608 1 2 80.700 1.010 112 126 0.564 1 1 9 1.651 2.198 176 208 0.722 1.5 1 10 1.7072.456 216 286 0.748 1 1 11 1.118 1.487 148 186 0.665 1 1 12 1 2 13 1.0001.706 140 254 0.651 3 1 14 1.531 1.688 240 314 0.697 1 1 15 1.372 2.372189 336 0.693 1 1 16 0.439 0.475 89 104 0.551 1 1 17 0.437 0.849 81 1720.485 4 1 18 0.801 1.313 150 224 0.527 5 3 19 1.356 2.237 177 360 0.7401 1 20 1.401 2.296 142 192 0.754 4 1 21 0.671 1.459 95 190 0.708 2 1 222.223 3.122 246 312 0.650 1 3 Control 0.939 1.273 303 377 0.522* Focus Dailies Lenses (−1.00 D)¹Pin Hole Test: 1 = very good, 5 = fail²This is visual clarity after autoclaving; 1 = clear, 5 = hazy

EXAMPLE 13

Poly N-vinyl pyrrolidone (NVP) polymers, PVK-15 and PVK-30, are suppliedby International Specialty Products. The NVP polymers are used as 30%(w/w/) solutions in deionized water. The PVK-15 has a molecular weightof about 9,700 and the PVK-30 has a molecular weight of about 67,000.

The NVP polymers are blended with nelfilcon to prepare a series ofsamples for making contact lenses. The composition of each of thesamples is listed in Table 21. Sample preparation is described asfollows. Nelfilcon aqueous solution (Example 1) is weighed in a cappedvial. The NVP polymer is weighed in another vial. The NVP polymersolution is added to the nelfilcon vial and mixed thoroughly.

Contact lenses are prepared from the above-prepared aqueous solutionaccording methods described in Example 2. Monomer solutions areirradiated at 1.9 mWcm⁻² for 10 seconds. Lenses are placed in glassvials containing isotonic borate buffered saline (saline solutioncontained 0.005% poloxomer) and then sterilized by autoclave.

Lens properties are reported in Table 21. All lenses are clear afterautoclaving. Lens properties (stress at break, elongation at break andmodulus) decrease linearly with increasing content of NVP polymer. Thediminution of lens properties (stress at break, elongation at break andmodulus) is greater for the NVP polymer having a higher molecularweight. This behavior contrasts with behavior, shown previously, ofcopolymers of N-vinyl pyrrolidone with hydrophobic comonomers such asvinyl acetate and 1-butene. The hydrophobic comonomers add reinforcementas shown by the increases in one or more key lens properties. TABLE 21Composition Center Stress at Elongation (Wt. Fraction) DiameterThickness Break at Break Modulus Sample No. Nelfilcon NVP polymer (mm)(mm) (N/mm²) (%) (N/mm²) 1 0.8983 0.1017^(a) 13.98 0.267 1.418 562 0.3562 0.7953 0.2047^(a) 13.93 0.274 2.312 442 0.356 3 0.7057 0.2943^(a)13.85 0.263 1.560 371 0.367 4 0.9004 0.0996^(b) 13.83 0.269 1.375 4210.399 5 0.8002 0.1998^(b) 13.96 0.268 1.205 385 0.376 6 0.69990.3001^(b) 14.01 0.264 1.268 379 0.344 Control 1.0000 13.80 0.266 0.370276 0.276^(a)PVK-15^(b)PVK-30Evidently the hydrophobic groups are required to give reinforcement. Thediminution of properties with the pure n-vinyl pyrrolidone polymer blendwith nelfilcon could result from the decrease in cross-link densitysince these polymers are not co-curable. However, the dilution ofcross-link density does not explain the increase in physical propertieswhen nelfilcon is blended with non-curing N-vinylpyrrolidone/hydrophobic monomer copolymers.

1. A polymerizable material for making an ophthalmic device, comprising:a water-soluble polyvinyl alcohol having crosslinkable groups; and amodifier in an amount sufficient to improve one or more physicalproperties of the ophthalmic device made from the polymerizablematerial, wherein the one or more physical properties are selected fromthe group consisting of stress at break (N/mm²), percentage ofelongation at break, toughness or energy to break (N·mm), andsusceptibility to fracture.
 2. A polymerizable material of claim 1,wherein said modifier is selected from the group consisting ofnanoparticles having a hydrophilic surface, a copolymer havinghydrophobic groups or units for imparting at least one desired physicalproperty to said ophthalmic device and hydrophilic groups or units in anamount sufficient to render the copolymer miscible with the polyvinylalcohol, and mixtures thereof.
 3. A polymerizable material of claim 2,wherein said water-soluble polyvinyl alcohol is a polyhydroxyl compoundwhich has a weight average molecular weight of at least about 2000 andwhich comprises from about 0.5 to about 80%, based on the number ofhydroxyl groups in the poly(vinyl alcohol), of units of the formula I, Iand II, I and III, or I and II and III

in which R is alkylene having up to 12 carbon atoms, R₁ is hydrogen orlower alkyl, R₂ is an olefinically unsaturated, electron-withdrawing,crosslinkable radical having up to 25 carbon atoms, and R₃ is hydrogen,a C₁-C₆ alkyl group or a cycloalkyl group,

wherein R and R₃ are as defined above, and R₇ is a primary, secondary ortertiary amino group or a quaternary amino group of the formulaN⁺(R′)₃X⁻, in which each R′, independently of the others, is hydrogen ora C₁-C₄ alkyl radical and X is HSO₄ ⁻, F⁻, Cl⁻, Br⁻, I⁻, CH₃COO⁻, OH⁻,BF⁻, or H₂PO₄ ⁻,

in which R and R₃ are as defined above, and R₈ is the radical of amonobasic, dibasic or tribasic, saturated or unsaturated, aliphatic oraromatic organic acid or sulfonic acid.
 4. A polymerizable material ofclaim 3, wherein said water-soluble polyvinyl alcohol is a polyhydroxylcompound which has a molecular weight of at least about 2000 and whichcomprises from about 0.5 to about 80%, based on the number of hydroxylgroups in the poly(vinyl alcohol), of units of the formula I, wherein R₂is a radical of formula IV or formula V—CO—NH—(R—NH—CO—O)_(q)—R₆—O—CO—R₄  (IV)—[CO—N H—(R—NH—CO—O)_(q)—R₆—O]_(p)—CO—R₄  (V) in which p and q,independently of one another, are zero or one, and R₅ and R₆,independently of one another, are lower alkylene having 2 to 8 carbonatoms, arylene having 6 to 12 carbon atoms, a saturated bivalentcycloaliphatic group having 6 to 10 carbon atoms, arylenealkylene oralkylenearylene having 7 to 14 carbon atoms or arylenealkylenearylenehaving 13 to 16 carbon atoms, and in which R₄ is an olefinicallyunsaturated copolymerizable radical having 2 to 24 carbone atoms,preferably having 2 to 8 carbonatoms, more preferably having 2 to 4carbon atoms.
 5. A polymerizable material of claim 3, wherein saidmodifier is composed of the nanopaticles having a hydrophilic surface.6. A polymerizable material of claim 5, wherein the nanoparticles arenano-sized silica fillers.
 7. A polymerizable material of claim 3,wherein said modifier is composed of one or more copolymers each havinghydrophobic groups or units for imparting at least one desired physicalproperty to said ophthalmic device and hydrophilic groups or units in anamount sufficient to render the copolymer miscible with thecrosslinkable polyvinyl alcohol.
 8. A polymerizable material of claim 7,wherein said modifier is a N-vinyl lactam copolymer which is acopolymerization product of at least one N-vinyl lactam with one or morehydrophobic monomer, wherein said at least one N-vinyl lactam has astructure of formula (VI)

in which R₁ g is an alkylene di-radical having from 2 to 8 carbon atoms,R₂₀ is hydrogen, C₁-C₇ alkyl, aryl having up to 10 carbon atoms, aralkylor alkaryl having up to 14 carbon atoms, and R₂₁ is hydrogen or loweralkyl having up to 7 carbon atoms.
 9. A polymerizable material of claim8, wherein said N-vinyl lactam is N-vinyl pyrrolidone.
 10. Apolymerizable material of claim 7, wherein said modifier is aN,N-dialkylmethacrylamide copolymer which is a copolymerization productof a N,N-di-C₂-C₄ alkyl methacrylamide with at least one hydrophobicmonomer.
 11. A polymerizable material of claim 10, wherein theN,N-di-C₂-C₄ alkyl methacrylamide is N,N-dimethylmethacrylamide.
 12. Apolymerizable material of claim 7, wherein said modifier is anon-crosslinkable polyurethane having a molecular weight of at leastabout 2000, or a crosslinkable polyurethane.
 13. A polymerizablematerial of claim 12, wherein said non-crosslinkable polyurethane is thereaction product of an isocyanate-capped polyurethane with water andamine, wherein said crosslinkable polyurethane is the reaction productof the isocyanate-capped polyurethane with an ethylenically unsaturatedamine (primary or secondary amine) or an ethylenically unsaturatedmonohydroxy compound, wherein said isocyanate-capped polyurethane is acopolymerization product of (a) at least one polyalkylene glycol offormulaHO—(R₉—O)_(n)—(R₁₀—O)_(m)—(R₁₁—O)_(l)—H  (1)  wherein R₉, R₁₀, and R₁₁,independently of one other, are each linear or branched C₂-C₄-alkylene,and n, m and l, independently of one another, are each a number from 0to 100, wherein the sum of (n+m+l) is 5 to 100, (b) at least onebranching agent selected from the group consisting of (i) a linear orbranched aliphatic polyhydroxy compound of formulaR₁₂—(OH)_(x)  (2), wherein R₁₂ is a linear or branched C₃-C₁₈ aliphaticmulti-valent radical and x is a number ≧3, (ii) a polyether polyol,which is the polymerization product of a compound of formula (2) and aglycol, (iii) a polyester polyol, which is the polymerization product ofa compound of formula (2), a dicarboxylic acid or a derivative thereofand a diol, and (iv) a cycloaliphatic polyol selected from the groupconsisting of a C₅-C₈-cycloalkane which is substituted by ≧3 hydroxygroups and which is unsubstituted by alkyl radical, a C₅-C₈-cycloalkanewhich is substituted by ≧3 hydroxy groups and which is substituted byone ore more C₁-C₄ alkyl radicals, and an unsubstituted mono- anddisaccharide, (v) an aralkyl polyol having at least three hydroxy C₁-C₄alkyl radicals, and (c) at least one di- or polyisocyanate of formulaR₁₃—(NCO)_(y)  (3) wherein R₁₃ the multivalent radical of a linear orbranched C₃-C₂₄ aliphatic polyisocyanate, the multivalent radical of aC₃-C₂₄ cycloaliphatic or aliphatic-cycloaliphatic polyisocyanate, or themultivalent radical of a C₃-C₂₄ aromatic or araliphatic polyisocyanate,and y is a number from 2 to 6, wherein said ethylenically unsaturatedmonohydroxy compound is a hydroxy-substituted lower alkylacrylate, ahydroxy-substituted lower alkylmethacrylate, a hydroxy-substituted loweralkyl-acrylamides, a hydroxy-substituted lower alkyl-methacrylamide, ora hydroxy-substituted lower alkylvinylether, wherein said ethylenicallyunsaturated amine has formula (4), (4′) or (4″)

In which, •l, j and k, independent of one another, are o or 1; R₁₄ ishydrogen, a linear or branched C₁-C₂₄ alkyl, a C₂-C₂₄ alkoxyalkyl, aC₂-C₂₄ alkylcarbonyl, a C₂-C₂₄ alkoxycarbonyl, an unsubstituted or C₁-C₄alkyl- or C₁-C₄ alkoxy-substituted C₆-C₁₀ aryl, a C₇-C₁₈ aralkyl, aC₁₃-C₂₂ arylalkylaryl, a C₃-C₈ cycloalkyl, a C₄-C₁₄ cycloalkylalkyl, aC₇-C₁₈ cycloalkylalkylcycloalkyl, a C₅-C₂₀ alkylcycloalkylalkyl, or analiphatic-heterocyclic radical; Z is a C₁-C₁₂ alkylene radical,phenylene radical or C₇-C₁₂ aralkylene radical; R₁₅ and R₁₅′,independently of each other, are hydrogen, C₁-C₄ alkyl or halogen; and Qis a radical of formula (5)

wherein r is the number 0 or 1, each of R₁₆ and R₁₇ independently of theother is hydrogen, C₁-C₄ alkyl, phenyl, carboxy or halogen, R₁₈ ishydrogen, C₁-C₄ alkyl or halogen, and Z′ is a linear or branched C₁-C₁₂alkylene, an unsubstituted phenylene, an C₁-C₄ alkyl- or C₁-C₄alkoxy-substituted phenylene, or a C₇-C₁₂ aralkylene.
 14. Apolymerizable material of claim 13, wherein component (a) consists ofone or more pblyalkylene glycols of formula (1a)HO—(CH₂—CH₂—O)_(n)—(CHY₁—CHY₂—O)_(m)—H  (1a) wherein one of radicals Y₁and Y₂ signifies methyl and the other radical signifies hydrogen, and nand m, independently of one another, each denote a number from 0 to 50,wherein the sum of (n+m) is 8 to 50, wherein component (b) consists ofone or more linear or branched aliphatic polyhydroxy compounds offormula (2), in which x is a number from 3 to 8, wherein component (c)consists of one or more diisocyanates of formula (3a)OCN—R₅—NCO  (3a) wherein R₅ is a linear or branched C₃-C₁₈-alkylene, anunsubstituted or C₁-C₄-alkyl-substituted or C₁-C₄-alkoxy-substitutedC₆-C₁₀-arylene, a C₇-C₁₈-aralkylene, aC₆-C₁₀-arylene-C₁-C₂-alkylene-C₆-C₁₀-arylene, a C₃-C₈-cyclo-alkylene, aC₃-C₈-cycloalkylene-C₁-C₆-alkylene, aC₃-C₈-cycloalkylene-C₁-C₂-alkylene-C₃-C₈-cycloalkylene, or aC₁-C₆-alkylene-C₃-C₈-cycloalkylene-C₁-C₆-alkylene, wherein saidethylenically unsaturated amine is selected from the group consisting ofmono-C₁-C₄ alkylamino-C₁-C₄ alkyl-acrylates, mono-C₁-C₄ alkylamino-C₁-C₄alkyl-methacrylates, di-C₁-C₄ alkylamino-C₁-C₄ alkyl-acrylates anddi-C₁-C₄ alkylamino-C₁-C₄ alkyl-methacrylates, and wherein saidethylenically unsaturated hydroxy compound is selected from the groupconsisting of hydroxy-substituted C₁-C₆ alkylacrylates andhydroxy-substituted C₁-C₆ alkylmethacrylates.
 15. A polymerizablematerial of claim 14, wherein said ethylenically unsaturated amine is2-terbutylaminoethylmethacrylate or 2-terbutylaminoethylacrylate,wherein said ethylenically unsaturated hydroxy compound is2-hydroxyethylmethacrylate or 2-hydroxyehtylcrylate, wherein component(c) consists of a diisocyanate selected from the group consistingisophorone diisocyanate (IPDI), toluylene-2,4-diisocyanate (TDI),methylenebis(cyclohexyl-isocyanate),1,6-diisocyanato-2,2,4-trimethyl-n-hexane (TMDI),methylenebis(phenyl-isocyanate) and hexamethylene-diisocyanate (HMDI).16. A polymeric article obtained by curing a polymerizable material ofclaim 2 in a mold.
 17. A polymeric article of claim 16, wherein saidpolymeric article is an ophthalmic device.
 18. An ophthalmic device ofclaim 17, wherein said ophthalmic device is a contact lens.
 19. Acontact lens of claim 18, wherein said water-soluble polyvinyl alcoholis a polyhydroxyl compound which has a weight average molecular weightof at least about 2000 and which comprises from about 0.5 to about 80%,based on the number of hydroxyl groups in the poly(vinyl alcohol), ofunits of the formula I, I and II, I and III, or I and II and III

in which R is alkylene having up to 12 carbon atoms, R₁ is hydrogen orlower alkyl, R₂ is an olefinically unsaturated, electron-withdrawing,crosslinkable radical having up to 25 carbon atoms, and R₃ is hydrogen,a C₁-C₆ alkyl group or a cycloalkyl group,

wherein R and R₃ are as defined above, and R₇ is a primary, secondary ortertiary amino group or a quaternary amino group of the formulaN⁺(R′)₃X⁻, in which each R′, independently of the others, is hydrogen ora C₁-C₄ alkyl radical and X is HSO₄ ⁻, F—, Cl⁻, Br⁻, I⁻, CH₃COO⁻, OH⁻,BF⁻, or H₂PO₄ ⁻,

in which R and R₃ are as defined above, and R₈ is the radical of amonobasic, dibasic or tribasic, saturated or unsaturated, aliphatic oraromatic organic acid or sulfonic acid.
 20. A contact lens of claim 19,wherein said water-soluble polyvinyl alcohol is a polyhydroxyl compoundwhich has a molecular weight of at least about 2000 and which comprisesfrom about 0.5 to about 80%, based on the number of hydroxyl groups inthe poly(vinyl alcohol), of units of the formula I, wherein R₂ is aradical of formula IV or formula V—CO—NH—(R₅—NH—CO—O)_(q)—R₆—O—CO—R₄  (IV)—[CO—NH—(R₅—NH—CO—O)_(q)—R₆—O]_(p)—CO—R₄  (V) in which p and q,independently of one another, are zero or one, and R₅ and R₆,independently of one another, are lower alkylene having 2 to 8 carbonatoms, arylene having 6 to 12 carbon atoms, a saturated bivalentcycloaliphatic group having 6 to 10 carbon atoms, arylenealkylene oralkylenearylene having 7 to 14 carbon atoms or arylenealkylenearylenehaving 13 to 16 carbon atoms, and in which R₄ is an olefinicallyunsaturated copolymerizable radical having 2 to 24 carbone atoms,preferably having 2 to 8 carbonatoms, more preferably having 2 to 4carbon atoms.
 21. A contact lens of claim 19, wherein said modifier iscomposed of the nanopaticles having a hydrophilic surface.
 22. A contactlens of claim 21, wherein the nanoparticles are nano-sized silicafillers.
 23. A contact lens of claim 19, wherein said modifier iscomposed of one or more copolymers each having hydrophobic groups orunits for imparting at least one desired physical property to saidophthalmic device and hydrophilic groups or units in an amountsufficient to render the copolymer miscible with the crosslinkablepolyvinyl alcohol.
 24. A contact lens of claim 23, wherein said modifieris a N-vinyl lactam copolymer which is a copolymerization product of atleast one N-vinyl lactam with one or more hydrophobic monomer, whereinsaid at least one N-vinyl lactam has a structure of formula (VI)

in which R₁ g is an alkylene di-radical having from 2 to 8 carbon atoms,R₂₀ is hydrogen, C₁-C₇ alkyl, aryl having up to 10 carbon atoms, aralkylor alkaryl having up to 14 carbon atoms, and R₂₁ is hydrogen or loweralkyl having up to 7 carbon atoms.
 25. A contact lens of claim 24,wherein said N-vinyl lactam is N-vinyl pyrrolidone.
 26. A contact lensof claim 23, wherein said modifier is a N,N-dialkylmethacrylamidecopolymer which is a copolymerization product of a N,N-di-C₂-C₄ alkylmethacrylamide with at least one hydrophobic monomer.
 27. A contact lensof claim 26, wherein the N,N-di-C₂-C₄ alkyl methacrylamide isN,N-dimethylmethacrylamide.
 28. A contact lens of claim 23, wherein saidmodifier is a non-crosslinkable polyurethane having a molecular weightof at least about 2000, or a crosslinkable polyurethane.
 29. A contactlens of claim 28, wherein said non-crosslinkable polyurethane is thereaction product of an isocyanate-capped polyurethane with water andamine, wherein said crosslinkable polyurethane is the reaction productof the isocyanate-capped polyurethane with an ethylenically unsaturatedamine (primary or secondary amine) or an ethylenically unsaturatedmonohydroxy compound, wherein said isocyanate-capped polyurethane is acopolymerization product of (a) at least one polyalkylene glycol offormulaHO—(R₉—O)_(n)—(R₁₀—O)_(m)—(R₁₁—O)_(l)—H  (1)  wherein R₉, R₁₀, and R₁₁,independently of one other, are each linear or branched C₂-C₄-alkylene,and n, m and 1, independently of one another, are each a number from 0to 100, wherein the sum of (n+m+l) is 5 to 100, (b) at least onebranching agent selected from the group consisting of (i) a linear orbranched aliphatic polyhydroxy compound of formulaR₁₂—(OH)_(x)  (2), wherein R₁₂ is a linear or branched C₃-C₁₈ aliphaticmulti-valent radical and x is a number ≧3, (ii) a polyether polyol,which is the polymerization product of a compound of formula (2) and aglycol, (iii) a polyester polyol, which is the polymerization product ofa compound of formula (2), a dicarboxylic acid or a derivative thereofand a diol, and (iv) a cycloaliphatic polyol selected from the groupconsisting of a C₅-C₈-cycloalkane which is substituted by ≧3 hydroxygroups and which is unsubstituted by alkyl radical, a C₅-C₉-cycloalkanewhich is substituted by ≧3 hydroxy groups and which is substituted byone ore more C₁-C₄ alkyl radicals, and an unsubstituted mono- anddisaccharide, (v) an aralkyl polyol having at least three hydroxy C₁-C₄alkyl radicals, and (c) at least one di- or polyisocyanate of formulaR₁₃—(NCO)_(y)  (3)  wherein R₁₃ the multivalent radical of a linear orbranched C₃-C₂₄ aliphatic polyisocyanate, the multivalent radical of aC₃-C₂₄ cycloaliphatic or aliphatic-cycloaliphatic polyisocyanate, or themultivalent radical of a C₃-C₂₄ aromatic or araliphatic polyisocyanate,and y is a number from 2 to 6, wherein said ethylenically unsaturatedmonohydroxy compound is a hydroxy-substituted lower alkylacrylate, ahydroxy-substituted lower alkylmethacrylate, a hydroxy-substituted loweralkyl-acrylamides, a hydroxy-substituted lower alkyl-methacrylamide, ora hydroxy-substituted lower alkylvinylether, wherein said ethylenicallyunsaturated amine has formula (4), (4′) or (4″)

In which, l, j and k, independent of one another, are o or 1; R₁₄ ishydrogen, a linear or branched C₁-C₂₄ alkyl, a C₂-C₂₄ alkoxyalkyl, aC₂-C₂₄ alkylcarbonyl, a C₂-C₂₄ alkoxycarbonyl, an unsubstituted or C₁-C₄alkyl- or C₁-C₄ alkoxy-substituted C₆-C₁₀ aryl, a C₇-C₁₈ aralkyl, aC₁₃-C₂₂ arylalkylaryl, a C₃-C₈ cycloalkyl, a C₄-C₁₄ cycloalkylalkyl, aC₇-C₁₈ cycloalkylalkylcycloalkyl, a C₅-C₂₀ alkylcycloalkylalkyl, or analiphatic-heterocyclic radical; Z is a C₁-C₁₋₂ alkylene radical,phenylene radical or C₇-C₁₂ aralkylene radical; R₁₅ and R₁₅′,independently of each other, are hydrogen, C₁-C₄ alkyl or halogen; and Qis a radical of formula (5)

wherein r is the number 0 or 1, each of R₁₆ and R₁₇ independently of theother is hydrogen, C₁-C₄ alkyl, phenyl, carboxy or halogen, R₁₈ ishydrogen, C₁-C₄ alkyl or halogen, and Z′ is a linear or branched C₁-C₁₋₂alkylene, an unsubstituted phenylene, an C₁-C₄ alkyl- or C₁-C₄alkoxy-substituted phenylene, or a C₇-C₁₂ aralkylene.
 30. A contact lensof claim 29, wherein component (a) consists of one or more polyalkyleneglycols of formula (Ia)HO—(CH₂—CH₂—O)_(n)—(CHY₁—CHY₂—O)_(m)—H  (1a) wherein one of radicals Y₁and Y₂ signifies methyl and the other radical signifies hydrogen, and nand m, independently of one another, each denote a number from 0 to 50,wherein the sum of (n+m) is 8 to 50, wherein component (b) consists ofone or more linear or branched aliphatic polyhydroxy compounds offormula (2), in which x is a number from 3 to 8, wherein component (c)consists of one or more diisocyanates of formula (3a)OCN—R₅—NCO  (3a) wherein R₅ is a linear or branched C₃-C₁₈-alkylene, anunsubstituted or C₁-C₄-alkyl-substituted or C₁-C₄-alkoxy-substitutedC₆-C₁₀-arylene, a C₇-C₁₈-aralkylene, aC₆-C₁₀-arylene-C₁-C₂-alkylene-C₆-C₁₀-arylene, a C₃-C₈-cyclo-alkylene, aC₃-C₈-cycloalkylene-C₁-C₆-alkylene, aC₃-C₈-cycloalkylene-C₁-C₂-alkylene-C₃-C₈-cycloalkylene, or aC₁-C₆-alkylene-C₃-C₈-cycloalkylene-C₁-C₆-alkylene, wherein saidethylenically unsaturated amine is selected from the group consisting ofmono-C₁-C₄ alkylamino-C₁-C₄ alkyl-acrylates, mono-C₁-C₄ alkylamino-C₁-C₄alkyl-methacrylates, di-C₁-C₄ alkylamino-C₁-C₄ alkyl-acrylates anddi-C₁-C₄ alkylamino-C₁-C₄ alkyl-methacrylates, and wherein saidethylenically unsaturated hydroxy compound is selected from the groupconsisting of hydroxy-substituted C₁-C₆ alkylacrylates andhydroxy-substituted C₁-C₆ alkylmethacrylates.
 31. A contact lens ofclaim 30, wherein said ethylenically unsaturated amine is2-terbutylaminoethylmethacrylate or 2-terbutylaminoethylacrylate,wherein said ethylenically unsaturated hydroxy compound is2-hydroxyethylmethacrylate or 2-hydroxyehtylcrylate, wherein component(c) consists of a diisocyanate selected from the group consistingisophorone diisocyanate (IPDI), toluylene-2,4-diisocyanate (TD I),methylenebis(cyclohexyl-isocyanate),1,6-diisocyanato-2,2,4-trimethyl-n-hexane (TMDI),methylenebis(phenyl-isocyanate) and hexamethylene-diisocyanate (HMDI).32. A method for making an ophthalmic device, comprising the steps of:(I) introducing a polymerizable material comprising a water-solublepolyvinyl alcohol having crosslinkable groups, a modifier in an amountsufficient to improve one or more physical properties of the ophthalmicdevice made from the polymerizable material, and optionally aphoto-initiator, into a mold, wherein said modifier is selected from thegroup consisting of nanoparticles having a hydrophilic surface, acopolymer having hydrophobic groups or units for imparting at least onedesired physical property to said ophthalmic device and hydrophilicgroups or units in an amount sufficient to render the copolymer misciblewith the polyvinyl alcohol, and mixtures thereof, wherein the one ormore physical properties are selected from the group consisting ofstress at break (N/mm²), percentage of elongation at break, toughness orenergy to break (N·mm), and susceptibility to fracture; (II)crosslinking by actinic radiation the polymerizable material; and (III)opening the mold so that the ophthalmic device can be removed from themold.
 33. A method of claim 32, wherein said water-soluble polyvinylalcohol is a polyhydroxyl compound which has a weight average molecularweight of at least about 2000 and which comprises from about 0.5 toabout 80%, based on the number of hydroxyl groups in the poly(vinylalcohol), of units of the formula I, I and II, I and III, or I and IIand III

in which R is alkylene having up to 12 carbon atoms, R₁ is hydrogen orlower alkyl, R₂ is an olefinically unsaturated, electron-withdrawing,crosslinkable radical having up to 25 carbon atoms, and R₃ is hydrogen,a C₁-C₆ alkyl group or a cycloalkyl group,

wherein R and R₃ are as defined above, and R₇ is a primary, secondary ortertiary amino group or a quaternary amino group of the formulaN⁺(R′)₃X⁻, in which each R′, independently of the others, is hydrogen ora C₁-C₄ alkyl radical and X is HSO₄ ⁻, F⁻, Cl⁻, Br⁻, I⁻, CH₃COO⁻, OH⁻,BF⁻, or H₂PO⁴⁻,

in which R and R₃ are as defined above, and R₈ is the radical of amonobasic, dibasic or tribasic, saturated or unsaturated, aliphatic oraromatic organic acid or sulfonic acid.
 34. A method of claim 33,wherein said modifier is composed of the nanopaticles having ahydrophilic surface.
 35. A method of claim 33, wherein said modifier iscomposed of one or more copolymers each having hydrophobic groups orunits for imparting at least one desired physical property to saidophthalmic device and hydrophilic groups or units in an amountsufficient to render the copolymer miscible with the crosslinkablepolyvinyl alcohol.
 36. A method of claim 35, wherein said modifier is aN-vinyl lactam copolymer which is a copolymerization product of at leastone N-vinyl lactam with one or more hydrophobic monomer, wherein said atleast one N-vinyl lactam has a structure of formula (VI)

in which R₁₉ is an alkylene di-radical having from 2 to 8 carbon atoms,R₂₀ is hydrogen, C₁-C₇ alkyl, aryl having up to 10 carbon atoms, aralkylor alkaryl having up to 14 carbon atoms, and R₂₁ is hydrogen or loweralkyl having up to 7 carbon atoms.
 37. A method of claim 35, whereinsaid modifier is a N,N-dialkylmethacrylamide copolymer which is acopolymerization product of a N,N-di-C₂-C₄ alkyl methacrylamide with atleast one hydrophobic monomer.
 38. A method of claim 35, wherein saidmodifier is a non-crosslinkable polyurethane having a molecular weightof at least about 2000, or a crosslinkable polyurethane.
 39. A method ofclaim 38, wherein said non-crosslinkable polyurethane is the reactionproduct of an isocyanate-capped polyurethane with water and amine,wherein said crosslinkable polyurethane is the reaction product of theisocyanate-capped polyurethane with an ethylenically unsaturated amine(primary or secondary amine) or an ethylenically unsaturated monohydroxycompound, wherein said isocyanate-capped polyurethane is acopolymerization product of (a) at least one polyalkylene glycol offormulaHO—(R₉—O)_(n)—(R₁₀—O)_(m)—(R₁₁—O)_(l)—H  (1)  wherein R₉, R₁₀, and R₁₁,independently of one other, are each linear or branched C₂-C₄-alkylene,and n, m and l, independently of one another, are each a number from 0to 100, wherein the sum of (n+m+l) is 5 to 100, (b) at least onebranching agent selected from the group consisting of (i) a linear orbranched aliphatic polyhydroxy compound of formulaR₁₂—(OH)_(x)  (2), wherein R₁₂ is a linear or branched C₃-C₁₈ aliphaticmulti-valent radical and x is a number ≧3, (ii) a polyether polyol,which is the polymerization product of a compound of formula (2) and aglycol, (iii) a polyester polyol, which is the polymerization product ofa compound of formula (2), a dicarboxylic acid or a derivative thereofand a diol, and (iv) a cycloaliphatic polyol selected from the groupconsisting of a C₅-C₈-cycloalkane which is substituted by ≧3 hydroxygroups and which is unsubstituted by alkyl radical, a C₅-C₈-cycloalkanewhich is substituted by ≧3 hydroxy groups and which is substituted byone ore more C₁-C₄ alkyl radicals, and an unsubstituted mono- anddisaccharide, (v) an aralkyl polyol having at least three hydroxy C₁-C₄alkyl radicals, and (c) at least one di- or polyisocyanate of formulaR₁₃—(NCO)_(y)  (3) wherein R₁₃ the multivalent radical of a linear orbranched C₃-C₂₄ aliphatic polyisocyanate, the multivalent radical of aC₃-C₂₄ cycloaliphatic or aliphatic-cycloaliphatic polyisocyanate, or themultivalent radical of a C₃-C₂₄ aromatic or araliphatic polyisocyanate,and y is a number from 2 to 6, wherein said ethylenically unsaturatedmonohydroxy compound is a hydroxy-substituted lower alkylacrylate, ahydroxy-substituted lower alkylmethacrylate, a hydroxy-substituted loweralkyl-acrylamides, a hydroxy-substituted lower alkyl-methacrylamide, ora hydroxy-substituted lower alkylvinylether, wherein said ethylenicallyunsaturated amine has formula (4), (4′) or (4″)

In which, l, j and k, independent of one another, are o or 1; R₁₄ ishydrogen, a linear or branched C₁-C₂₄ alkyl, a C₂-C₂₄ alkoxyalkyl, aC₂-C₂₄ alkylcarbonyl, a C₂-C₂₄ alkoxycarbonyl, an unsubstituted or C₁-C₄alkyl- or C₁-C₄ alkoxy-substituted C₆-C₁₀ aryl, a C₇-C₁₈ aralkyl, aC₁₃-C₂₂ arylalkylaryl, a C₃-C₈ cycloalkyl, a C₄-C₁₄cycloalkylalkyl, aC₇-C₁₈ cycloalkylalkylcycloalkyl, a C₅-C₂₀ alkylcycloalkylalkyl, or analiphatic-heterocyclic radical; Z is a C₁-C₁₋₂ alkylene radical,phenylene radical or C₇-C₁₂ aralkylene radical; R₁₅ and R₁₅′,independently of each other, are hydrogen, C₁-C₄ alkyl or halogen; and Qis a radical of formula (5)

wherein r is the number 0 or 1, each of R₁₆ and R₁₇ independently of theother is hydrogen, C₁-C₄ alkyl, phenyl, carboxy or halogen, R₁₈ ishydrogen, C₁-C₄ alkyl or halogen, and Z′ is a linear or branched C₁-C₁₋₂alkylene, an unsubstituted phenylene, an C₁-C₄ alkyl- or C₁-C₄alkoxy-substituted phenylene, or a C₇-C₁₂ aralkylene.
 40. A method ofclaim 39, wherein component (a) consists of one or more polyalkyleneglycols of formula (Ia)HO—(CH₂—CH₂—O)_(n)—(CHY₁—CHY₂—O)_(m)—H  (1a) wherein one of radicals Y₁and Y₂ signifies methyl and the other radical signifies hydrogen, and nand m, independently of one another, each denote a number from 0 to 50,wherein the sum of (n+m) is 8 to 50, wherein component (b) consists ofone or more linear or branched aliphatic polyhydroxy compounds offormula (2), in which x is a number from 3 to 8, wherein component (c)consists of one or more diisocyanates of formula (3a)OCN—R₅—NCO  (3a) wherein R₅ is a linear or branched C₃-C₁₋₈-alkylene, anunsubstituted or C₁-C₄-alkyl-substituted or C₁-C₄-alkoxy-substitutedC₆-C₁₀-arylene, a C₇-C₁₈-aralkylene, aC₆-C₁₀-arylene-C₁-C₂-alkylene-C₆-C₁₀-arylene, a C₃-C₈-cyclo-alkylene, aC₃-C₈-cycloalkylene-C₁-C₆-alkylene, aC₃-C₈-cycloalkylene-C₁-C₂-alkylene-C₃-C₈-cycloalkylene, or aC₁-C₆-alkylene-C₃-C₈-cycloalkylene-C₁-C₆-alkylene, wherein saidethylenically unsaturated amine is selected from the group consisting ofmono-C₁-C₄ alkylamino-C₁-C₄ alkyl-acrylates, mono-C₁-C₄ alkylamino-C₁-C₄alkyl-methacrylates, di-C₁-C₄alkylamino-C₁-C₄alkyl-acrylates anddi-C₁-C₄alkylamino-C₁-C₄ alkyl-methacrylates, and wherein saidethylenically unsaturated hydroxy compound is selected from the groupconsisting of hydroxy-substituted C₁-C₆ alkylacrylates andhydroxy-substituted C₁-C₆ alkylmethacrylates.
 41. A method of claim 40,wherein said ethylenically unsaturated amine is2-terbutylaminbethylmethacrylate or 2-terbutylaminoethylacrylate,wherein said ethylenically unsaturated hydroxy compound is2-hydroxyethylmethacrylate or 2-hydroxyehtylcrylate, wherein component(c) consists of a diisocyanate selected from the group consistingisophorone diisocyanate (IPDI), toluylene-2,4-diisocyanate (TDI),methylenebis(cyclohexyl-isocyanate),1,6-diisocyanato-2,2,4-trimethyl-n-hexane (TMDI),methylenebis(phenyl-isocyanate) and hexamethylene-diisocyanate (HMDI).42. A method for modifying one or more physical properties of a hydrogelarticle obtained from the polymerization of a crosslinkable polymer,comprising the steps of: (I) adding, into a solution of saidcrosslinkable polymer, a modifier in an amount sufficient to modify saidone or more physical properties of said polymeric article, wherein saidmodifier is selected from the group consisting of nanoparticles having ahydrophilic surface, a copolymer having hydrophobic groups or units forimparting at least one desired physical property to said hydrogelarticle and hydrophilic groups or units in an amount sufficient torender it miscible with the crosslinkable polymer, and mixtures thereof;(II) mixing thoroughly said modifier and the crosslinkable polymer; and(III) crosslinking said crosslinkable polymer in the presence of themodifier to obtain said hydrogel article, wherein the one or morephysical properties are selected from the group consisting of stress atbreak (N/mm²), percentage of elongation at break, toughness or energy tobreak (N·mm), and susceptibility to fracture.
 43. A method of claim 42,wherein said modifier is composed of the nanopaticles having ahydrophilic surface.
 44. A method of claim 43, wherein said modifier iscomposed of the nanopaticles having a hydrophilic surface.
 45. A methodof claim 42, wherein said modifier is composed of one or more copolymerseach having hydrophobic groups or units for imparting at least onedesired physical property to said ophthalmic device and hydrophilicgroups or units in an amount sufficient to render the copolymer misciblewith the crosslinkable polymer.
 46. A method of claim 35, wherein eachof said one or more copolymers is a polymerization product of at leastone hydrophilic monomer and at least one hydrophobic monomer, whereinsaid hydrophilic is present in an amount sufficient to impart a desiredmiscibility with the crosslinkable polymer.